The SAT Question Everyone Got Wrong

Рет қаралды 11,651,338

6 ай бұрын

How an SAT question became a mathematical paradox. Head to brilliant.org/veritasium to start your free 30-day trial, and the first 200 people get 20% off an annual premium subscription.
Special thanks to our Patreon supporters! Join this list to help us keep our videos free, forever:
ve42.co/PatreonDEB
I invented Snatoms, a molecule modeling kit where the atoms snap together magnetically. Try it at ve42.co/SnatomsV
Huge thanks to Dr. Doug Jungreis for taking the time to speak with us about this SAT question.
Thanks to Stellarium, a wonderful free astronomy simulator - ve42.co/Stellarium
Thanks to Newspapers.com, a database of historical newspapers - ve42.co/Newspapers
▀▀▀
References:
Summary of this problem by MindYourDecisions - • Why did everyone miss ...
More cool math about this problem by Kyle Hill - • The SAT Question NO ON...
Discussion of a solar day by MinutePhysics - • Why December Has The L...
Murtagh, J. (2023). The SAT Problem That Everybody Got Wrong. Scientific American - ve42.co/SATSciAm
United Press International (1982). Error Found in S.A.T. Question. New York Times - ve42.co/SAT-NYT
Yang (2020). What's the hardest SAT math problem that you've seen? Quora - ve42.co/SATQuora
Coin rotation paradox via Wikipedia - ve42.co/CoinParadox
Simmons, B. (2015). Circle revolutions rolling around another circle. MathStackExchange. - ve42.co/CircleRoll
Sidereal time via Wikipedia - ve42.co/SiderealWiki
Solar Time vs. Sidereal Time via Las Cumbres Observatory - ve42.co/SiderealLCO
Images & Video:
Zotti, G., et al. (2021). The Simulated Sky: Stellarium for Cultural Astronomy Research - ve42.co/Stellarium
Newspapers from 1980s - 1990s via Newspapers.com - ve42.co/Newspapers
SAT Practice Test via the College Board - ve42.co/PracticeSAT
Revolution Definition via NASA - ve42.co/RevolutionNASA
Revolution Definition via Merriam-Webster - ve42.co/RevolutionWebster
Earth motion animation via NASA - ve42.co/OrbitNASA
Satellite animation via NASA - ve42.co/SatNASA
▀▀▀
Special thanks to our Patreon supporters:
Adam Foreman, Anton Ragin, Balkrishna Heroor, Bernard McGee, Bill Linder, Burt Humburg, Chris Harper, Dave Kircher, Diffbot, Evgeny Skvortsov, Gnare, John H. Austin, Jr., john kiehl, Josh Hibschman, Juan Benet, KeyWestr, Lee Redden, Marinus Kuivenhoven, Max Paladino, Meekay, meg noah, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Sam Lutfi, Stephen Wilcox, Tj Steyn, TTST, Ubiquity Ventures
▀▀▀
Directed by Emily Zhang
Written by Emily Zhang and Gregor Čavlović
Edited by Peter Nelson
Animated by Ivy Tello and Fabio Albertelli
Filmed by Derek Muller
Produced by Emily Zhang, Han Evans, Gregor Čavlović, and Derek Muller
Thumbnail by Ren Hurley
Additional video/photos supplied by Getty Images and Pond5
Music from Epidemic Sound

Пікірлер: 19 000

@duckyfam9012 2 ай бұрын

“I was amazed how badly it’s worded,” literally half of the SAT problems.

@LJ3783 2 ай бұрын

Y’all are overcomplicating a simple problem as an excuse for flunking out of community college

@NicholasAndre1 2 ай бұрын

@@LJ3783I think there’s a greater theme here - there’s a certain hubris to the belief that questions such as this represent “intelligence.” There are…certain large tech companies that exclusively leverage SAT type philosophies in hiring to the exclusion of allowing nuance, and it doesn’t actually work that well in my opinion. Problems in the real world often don’t look like an SAT question and more often there literally isn’t a “correct” answer. If we condition people on these sorts of problems they don’t end up adapting well to an engineering trade off, nor are people who view the world from an SAT lens necessarily good at solving trade-offs in the context of a team. I think this type of criticism is that the SAT quite obviously fails to support its own philosophy of the existence of “correct answers” when the wording is wrong. I don’t say that to explain away my life failures, rather I say that because I have learned the importance of hiring people in a more nuanced way that allows for these different dimensions. Not sure if you’ve ever tried to work with an arrogant math PhD before 😂

@justarandomguy8694 2 ай бұрын

@@LJ3783not really. The wording here is objectively bad, and dare I say, wrong.

@LJ3783 2 ай бұрын

@@justarandomguy8694I'd say that's the real issue, it comes down to semantics.

@cameronschyuder9034 2 ай бұрын

@@LJ3783if the wording is bad enough that most everyone got it wrong, then perhaps there needs to be an evaluation instead of brushing it off as semantics. Usually with tests like these it is expected for some people to get it wrong. But not a vast majority. If you say things poorly, then it makes sense that you get misunderstandings. Also, you cannot flunk out of community college if you’re not even in college. These exams are meant to loosely determine how ready you are for college. I’m not sure what your first comment was meant to say

@KevinJDildonik 6 ай бұрын

To all the 1st posters: KZfaq takes up to 15 minutes to gather data on a video before showing stats. Everyone in the first 15 minutes all think they're first.

@savitatawade2403 6 ай бұрын

😂

@kakyoindonut3213 6 ай бұрын

Nuh uh

@Warr4real 6 ай бұрын

I’m 9 minutes in and I says 12k views and 150 comments

@MrDJ2004 6 ай бұрын

haha

@TeachAManToAngle 6 ай бұрын

Yeah but I was first before you even wrote this. . .

@NoraOlson-ct7nr 2 ай бұрын

Having the small circle rotating 3 times with the camera rotating is the best intuitive explanation of what's going on I've ever seen for something like this

@thatonecrossiant22 2 ай бұрын

It was the perfect explanation

@anonymousguy5694 Ай бұрын

I solved the question at the start of the video by pausing the video. MF I got 4 and then wondering the whole video why did people mark 3💀

@juhaniu6371 Ай бұрын

@@anonymousguy5694 because they just wanted to answer something and there was no checkbox for the answer 4? so they assumed they are missing something and marked 3.

@EmmaSquire-ks9nu Ай бұрын

I didn't watch the video. But it is 3 right? Because the small circle would spin 3.141592653589etc x(radius x2) for about 6.28 before going a full rotation, while the bigger circle would spin closer to a distance equal to 18.84.

@yolanda6392 Ай бұрын

@@EmmaSquire-ks9nuWatch it and you’ll see it’s 4. But 3 from the perspective of inside the circle (i think that’s how you word it)

@-ADOI- Ай бұрын

I was so confused because of the word "revolution," "1" is what I thought the answer was because of that

@engrpas 11 күн бұрын

Yes, there's a distinction between "rotation" and .revolution" The outer coin makes one revolution but several rotations.

@5MadMovieMakers 6 ай бұрын

This was a mentally challenging video to watch first thing in the morning. I'm awake now

@nirbhaykumarchaubey8777 6 ай бұрын

Wait, it is night

@krishmishra514 6 ай бұрын

It is 10 PM where I live and now I can't sleep😂

@zayansaifullah2008 6 ай бұрын

Bruh it’s 16:46 where I am Got back from school and just did some homework now I’m eating snacks then I will play games

@willson8394 6 ай бұрын

You're mentally challenged

@QuantyzIGuess 6 ай бұрын

@@zayansaifullah2008 same

@felixp535 6 ай бұрын

That part about the circle rotating around the triangle was mind-blowing. You instantly understand why it's not the same if the circle rolls on a flat line or rolls on a curved line

@Renegade605 6 ай бұрын

That was the "aha" moment for me too.

@misterscottintheway 6 ай бұрын

This

@argelovec6216 6 ай бұрын

There were 3 aha moments for me

@Marco-xz7rf 6 ай бұрын

if you divide the straight line in half and start to roll along it at the "top" to the end you then can make a 180, roll around to the "bottom" and then go in the other direction, make another 180 and keep going until you reach your starting point. These two 180 needed for the direction change add the 4th rotation 🤯

@NickyG-NZ 6 ай бұрын

The earth around the sun was a fantastic example for why the frame of reference matters, especially with the graphic

@NCore_._ 10 күн бұрын

I don't like math, but any visual explanation like this makes me engross in it for hours, replaying multiple sections to fully understand it and appreciate the fact, that how amazing it is.

@anirudhkodial1977 18 сағат бұрын

Start learning Houdini. You'll be jumping down an endless rabbit-hole.

@littlezombie9621 22 күн бұрын

Mathematically it‘s actually really easy to calculate. 1) Calculate the distance d that point A has to travel. If you think about it, that‘s not the circumference of circle B, but the circumference of the radius B plus the radius of A, creating a third circle C around point B with point A now on it‘s outline. The circumference of this new circle C is now the distance d that point A has to travel to get back to its starting position. Formula for circle circumference: 2 * r * PI Now we know that r = rB + rA and rB = 3 * rA -> d = 2 * (4 * rA) * PI = 8 * rA * PI 2) Calculate the distance dRev that circle A covers with one revolution, which is equals the circumference of circle A. Again we use the formula for circumference, this time on circle A. -> dRev = 2 * rA * PI 3) Lastly, calculating the number of revolutions needed, we divide the total distance point A has to travel on d ( = circumference of circle C) by dRev (the circumference of A). -> R = d / dRev = (8 * rA * PI) / ( 2 * rA * PI) rA and PI cancel each other out. -> R = 8 / 2 = 4

@blinkers88 19 күн бұрын

"easy"

@tanez778 14 күн бұрын

@@blinkers88 I mean it's pretty easy if you understood the video, it's more or less exactly this part 9:45

@varjain 4 күн бұрын

Yeah "easy" SATs dont have enough time to calculate that you know

@abrokeprogrammer 4 күн бұрын

Ikr Also... U didn't really need to write the whole second half The answer is simple The R is 4r then it's 4 times

@abrokeprogrammer 4 күн бұрын

@@tanez778the video is a waste of time for such a simple answer

@TupperWallace 6 ай бұрын

The 1872 novel “Around the World in Eighty Days” had a plot that depended on this kind of situation. Phileas Fogg traveled around the world eastward, against the earth’s rotation. Though initially he thought he’d missed the 80 day deadline by some hours, in fact only 79 days had passed in London. One extra rotation had passed beneath his feet. He won the prize, married the girl and lived happily ever after.

@LimeyLassen 6 ай бұрын

Fun!

@davidklein1245 6 ай бұрын

That is what first came to mind when I first saw this problem. I didn't immediately jump to 4 as the answer, but I knew 3 wasn't correct.

@Mark73 6 ай бұрын

There's a recent TV version starring David Tennant that I remember that from.

@wingracer1614 6 ай бұрын

@@Mark73 Really? I might have to check that out

@BoneyMB 6 ай бұрын

Glad about him.

@forkmonkey 5 ай бұрын

Another fun way to conceptualize the N+1 is to ask what happens if the circumference of B is 0. A still has to rotate around that point, one time. Great video.

@davidbesant 5 ай бұрын

Brilliant. Wish I'd thought of that!

@startibartfast42 5 ай бұрын

I thought of it as a circle rolling three times along a straight line, and then one more time as the straight line is curled into a circle itself

@fra_dp 5 ай бұрын

That's actually a great example.

@AsterothPrime 5 ай бұрын

Yes because by measuring from the center of the circle, you are offsetting by the value of the radius. So you essentially just add up each circle's radius to get the number of rotations of circle A. So if Circle B's radius was zero, the centre of circle A still has to travel around it's own radius of 1.

@budle89 5 ай бұрын

this helps a lot!! thanks!

@KyleHarris-dx9ns 22 күн бұрын

There are three (3) classes of portfolios each stages with their different prices and profits as well.

@GeraldLawson-xi3cz 22 күн бұрын

Could anyone kindly elaborate on ASHLEIGH PAIGE the advisor's background and qualifications! it’s actually my next move.

@CamilaPierre-ve4eh 22 күн бұрын

Certainly, there are a handful of experts in the field. I've experimented with a few over the past years, but I've stuck with AshleigAmerson for about five years now, and her performance has been consistently impressive.She’s quite known in her field, look-her up.

@CamilaPierre-ve4eh 22 күн бұрын

@ashleighpaige ...that's it = 4advice..

@CamilaPierre-ve4eh 22 күн бұрын

@ashleighpaige ...that's it = 4advice... Telegram chart..

@MaiChiPham-fz4tr 22 күн бұрын

SHE'S MOSTLY ON TELEGRAMS, USING THE USERNAME.......

@Awkward_migrant 2 ай бұрын

This explanation is the best i have found. The idea of the distance the centre of the planet circle travels and then deriving ratios makes the most sense to me and your graphics helped me to grasp this. It's fascinating. Not too mention the perspective element influencing the answer!! What i didn't realise is that the extra rotation is accounted for as well if observing from the perspective from the centre of the "sun" circle by the fact that the observer has to rotate once to continuously observe the "planet" circle

@Darth_Insidious 5 ай бұрын

I was confused for a second until I realized that if you set the radius of the big circle to 0, or in other words rotate the smaller circle around a point on its circumference, it takes 1 full rotation for the circle to end up back at the start.

@willdurneybenson 5 ай бұрын

this comment helped me solidify ny understanding thank you

@dr.albekhan8640 5 ай бұрын

Thanks. This is a great way to think about it! ❤❤

@solimao1236 5 ай бұрын

Genius comment, thank you!

@08-quocat6 5 ай бұрын

finally! i got it

@Nowolf 5 ай бұрын

That idea helped me as well

@Shepard-Thomas 6 ай бұрын

In college, I took a poetry class and once had an answer marked wrong on a test. Confident in my response, I reached out to the poet themselves, who affirmed I was right and even communicated this to my professor. Despite not being a fan of poetry, that moment made me quite proud!

@QYXP 6 ай бұрын

Did the professor change your grade?

@Sciguy95 6 ай бұрын

@@QYXPI had a question marked wrong on a chemistry test that the professor refused to accept was actually right. The head of the chemistry department came to our class and embarrassed him in front of everyone showing why I was right and he was wrong.

@VADemon 6 ай бұрын

literature tests: q.e.d.

@pongmaster123 6 ай бұрын

@@Sciguy95 very cool, but also unprofessional

@Derzull2468 6 ай бұрын

@@pongmaster123 We don't have the full backstory and never will, it might have been well deserved. Don't feel offended for some random obtuse chemistry teacher that may or may not even exist.

@fpgaguy 2 ай бұрын

I appreciate every one of your videos, they always make me think, and sometimes make my head hurt. Thank you.

@SuperJm1200 22 күн бұрын

Good job, very clear. My professor in computer science used to say that if you are a good programmer and you have an error in your code chances are you are usually off by 1 somewhere.

@Tim3.14 6 ай бұрын

One way to see the extra rotation -- shrink the inner circle to radius approximately 0, so it's like a thin wire. The circle still has to do a rotation to roll around the wire, even though the wire's circumference is negligible. (The rotation disappears from the "circle's perspective" because the "camera" does that one rotation along with it.)

@niels6186 6 ай бұрын

You’re clever 👌

@abhirammadhu2973 6 ай бұрын

That’s some pro level thinking🔥

@munkhjinbuyandelger 6 ай бұрын

but why is it one? why cant it be anything else?

@rambbler 6 ай бұрын

@@munkhjinbuyandelger10:10

@mmeettwwoo 6 ай бұрын

Where is the paradox, when started rotating around same sized coin, point under neck of face picture was touching, after halfrotation at 180 deg where narrator started speaking again, point above head of face picture was touching the stationary coin, that means half rotation, full rotation will be when same point that was touching the stationary coin will again touch it, and in same sized coins, that comes when coin reaches starting point again. So where is paradox?? Cant they see that point that was touching at start, touches the circle again at whole 360 rotation, in same size coins. What is confusion??

@user-rx4wo7il2g 5 ай бұрын

Thinking about this yesterday and I realized the extra rotation becomes intuitive if you shrink the large circle down to a point, and rotate around that. Even though the diameter of the circle it's rotating around is zero, the "small" circle still has to make a full rotation to return to its starting point.

@korkow 5 ай бұрын

Imo this is a more immediately intuitive explanation than what was in the video!

@kwimms 5 ай бұрын

This is a dumb fake question to convince you that the Earth is turning. These two clowns couldn't solve the time of day.

@user-ow1ui5pw6z 5 ай бұрын

I also thought of this same explanation

@brettgregory7799 5 ай бұрын

Excellent!

@crussty 5 ай бұрын

Great visualisation. This should be pinned

@josrthorst6316 2 ай бұрын

This is really interesting! I initially interpreted it as the revolutions answer (1) and was immediately very thrown off by the answer options. Very cool to learn about this type of math problem!

@robertnewton-bf3cy 28 күн бұрын

1) In case nobody has mentioned it yet (too many comments for me to read) you got the definition of a "sidereal year" slightly wrong. The sidereal year is Earth's orbital period. It's defined with respect to the distant stars (hence it's "sidereal"), but it's measured in SOLAR DAYS. Its length is about 365.256 mean solar days (24 hour days). The "solar year" is shorter than the sidereal year, but only by about 20 minutes.. A solar year is about 365.242 mean solar days. The difference is due to the "precession" of Earth's axis of rotation, not because of the difference in lengths of the solar day and the sidereal day. 2) As regards the length of a day, you talked about when the Sun is ovehead. I think you meant when the Sun is at its highest in the sky. Where I live the Sun is never overhead. 😃

@stevedietrich8936 5 ай бұрын

I came up with the answer, 3, in a second or two, and then wondered "how could that possibly be incorrect". I spent the next 18 minutes learning how. Great video!

@888cromartie 5 ай бұрын

An actual honest response, lol at those who said they instantly concluded it was 4 rotations

@enzolomongiello4497 5 ай бұрын

It is the kind of problems which when you see the solution you feel dumb because the solution is so obvious

@clarkkent4665 5 ай бұрын

You weren't incorrect

@jamiefa2000 5 ай бұрын

i was surprised cause my intuitive answer was 4 by looking at the circles but it was not an option so i thought 3 XD

@abinash446 5 ай бұрын

The answer is 3 only the video is useless

@ZEROBRICKS 6 ай бұрын

I learned about this problem when calculating gear ratios of planetary gearboxes, using exactly same 1:3 ratios.

@Dont_Read_My_Picture 6 ай бұрын

Don't read my nameDon't read my name

@hexagonal7708 6 ай бұрын

The same thing happened to me

@DrDipsh1t 6 ай бұрын

That was my exact thought was gear ratios lol.

@venanziadorromatagni1641 6 ай бұрын

Learned about this when we talked about the moon slowing down its rotation in high school and I realised it still made 1 rotation around its own axis for every lunar month, so it could always show the same face towards Earth.

@dminsanebros 6 ай бұрын

I was just wondering this. It is only for planetary gears or all gears?

@adolforabasa Ай бұрын

Another way to see it is using curvature. The (exterior) integral curvature of along any closed curve in the plane is 2pi (thus adding one). Interior on the other hand is -2pi due to the change of sign in the curvature vector (thus removing one). This is one of the interpretations of curvature: it tells you how longer (or shorter) a curve gets by looking at the points sitting at distance one from it, provided the set of such points is well defined (always defined for the distance of any convex set for instance).

@ozhotz5417 15 күн бұрын

Stick a pin in the table and rotate the coin around it. You will see that the coin rotates 1 time. Rotating the coin around 0 distance still takes a rotation, then you add the length of the coin if you rotate it around a coin, adding to make the 2 rotations.

@Spondre 6 ай бұрын

I loved the "I hope so" answer from Doug at the end. It highlights the most important lesson I learned during my education: "I might be wrong."

@hieronymusbutts7349 6 ай бұрын

I feel like I already had that lesson before education. I feel like the most important lesson for me - that helped me grapple with how to be effectively wrong - is how to think in terms of probability than binaries.

@zqzj 6 ай бұрын

@@hieronymusbutts7349❤

@glennpearson9348 6 ай бұрын

A harder lesson still is, "I might be wrong and I'll never know it." This is why people who fear the Scientific Method really shouldn't. It's also a primer in the Scientific Method, perfectly demonstrating why the goal isn't to prove a hypothesis is correct. Rather, the goal is to prove a hypothesis is NOT correct. Similarly, it demonstrates why the strongest theories are those derived from inductive reasoning (multiple specific cases lead to a generalized conclusion), rather than deductive reasoning (a generalized case leads to multiple specific conclusions).

@Xingchen_Yan 6 ай бұрын

Agreed! The most important thing I learned when learning math or physics or any objective knowledge is that by admitting the probability your are wrong is the best you can do to advance in those fields. I love to think that the physics, as we human know and define it, is always more correct than before but never (at least in the foreseeable future) completely right.

@myuzu_ 6 ай бұрын

I always thought this way, but I learned in the working world that if you acknowledge that you could be wrong other people will assume you're wrong.

@atticuscpchan 5 ай бұрын

4:20 Fun fact, the SAT actually tells you to assume all diagrams are drawn to scale unless otherwise indicated. Definetally made my life easier when I took it.

@scramjet7466 5 ай бұрын

Thats convenient. In Jee they purposefully distort it

@kernelsmith 5 ай бұрын

It didn't help you in the Writing and Language section...LOL, JK😂

@techgeek2625 5 ай бұрын

@@scramjet7466According to my experience most of them are close, if not to scale. Anyways scale doesn't really matter for the questions in JEE

@attsealevel 5 ай бұрын

techgeek2625 was right - whether it was drawn to scale (or not) - it didn't matter in this case. The outcome is always the same. total # of rotations = ratio between inner circle to outer circle + 2πr

@techgeek2625 5 ай бұрын

@@attsealevel Idk much about the questions of SAT, but judging by the level of SAT Maths, maybe some questions will be easier to solve with diagrams which are to scale.

@pikastudios2850 Ай бұрын

Here’s my guess, if the wheel A is revolving like a wheel then you divide both the circles circumference. Circle A has a radius of X and circle B has a radius of 3X, to find the circumference we multiply the radius by two and then times PI, making Circle A have a circumference of 2XPi and circle B having a circumference of 6X PI, so it should be 3

@mateofyt Ай бұрын

Exactly! They should open a dictionary. It's easy to solve anything if you change the question to fit your answer. By definition of a revolution, the number 3 is correct. Perfect analogy are gears or a wheel because as circle A the wheel would make only 3 REVOLUTIONS on circle B's circumference line, it literally can't make 4. Just because circle A looks like it made an extra full revolution from our perspective, doesn't mean it did. The only reason it looks like so is because, relative to us, circle A is literally getting pivoted full 360° once every time it travels circle B's full circumference. At 180° point circle A looks to us like a flipped version of what it looks like to circle B. If you make an upright square image travel forward on any circles circumference, it would literally get flipped for us at the half way point without making even a fraction of a revolution, that's why for that circle the image stays upright the whole time.

@humilulo 2 ай бұрын

i've learned more stuff from textbooks or reading on the internet than i have in school. i've seen 'sidereal' for more than a decade and never had any good understanding of what it was nor even how it was pronounced. now i learned both. thanks!!

@Cosmic9999 6 ай бұрын

It will never fail to amaze me how seemingly simple questions can turn out to go against common sense when studied further, and then can be used to add to knowledge and laws that are used to greatly change or enhance our world.

@GameTimeWhy 6 ай бұрын

This is why common sense is not a thing

@anteshell 6 ай бұрын

@@GameTimeWhy That's not at all what common sense is. Common sense is an ability to intuitively solve simple everyday problems such as "It is cold outside, I will wear warm clothes" or "it is raining, it is better to dry clothes inside". It is certainly not something you can use to solve complex math.

@wernerviehhauser94 6 ай бұрын

@@anteshellTrue. The major problem with "common sense" is that too many people equate "I think that...." with "It is common sense that....".

@sumermuktawat 6 ай бұрын

This channel information starts where common sense end. And there are many people who dont have common sense to start with

@Mallchad 6 ай бұрын

@@anteshellThis is a a hand-wavy explanation. Common sense is usually used to describe something that should be simple and intuitive and known by many people within a given area. This video shows why common sense doesn't map easily to reality and we should study things further. This also isn't complex math its basic geometry, the fundemental of math.

@gregnixon1296 5 ай бұрын

It makes the story even better to know that one of the students who found the SAT error became a mathematician.

@EagleOxford 5 ай бұрын

They should have offered him a job making the tests.

@FlorenceSlugcat 5 ай бұрын

The fact that he corrected a mistake from the very test that they use to determine if you were good at math probably is a good point to bring up to get hired or accepted for a job or university Its also nice to see that they aknowledged their mistake, admitted it to everyone in news, and dismissed the question from everyone’s test. They have admitted to everyone their mistake, knowing well that it would impact their reputation for having made the mistake Only 3 people in the whole country sent a letter to correct them, likely not many noticed or cared about the mistake. They could just “ignored it and pretend it didnt happen” like so many goverments and corporations do regularly. Even more so considering people were not sharing everything instantly using internet on a global scale

@zzzzzzz1zzzzzzzzzz1z 5 ай бұрын

dude if he became a social worker i'd be more fascinated

@jakemccoy 5 ай бұрын

@@FlorenceSlugcat Removing the question was improper and created more inaccuracy in the scores. The question was part of the test and consumed time that could have been used on other problems. At least some students failed to answer other questions correctly because they wasted time on this question. For example, a great math student could have spent 5 minutes on this question totally stumped that no correct answer was there. Now, that great math student gets this question thrown out and also gets some other questions wrong because of time. So, any student who answered 3 should have been given full credit. The test makers who allowed this faulty question also administered a faulty correction.

@gregnixon1296 5 ай бұрын

@@jakemccoy I agree the question should have been thrown out. When every student in one of my classes misses a question, I eliminate the item. This rarely happens, however.

@martinfaust2783 2 ай бұрын

Love this video. Good explanation of this math magic. Great job.

@anujbansal11 19 күн бұрын

Well this was so simple, got it right in the 1st attempt. The center of circle A is 4 units away from center of circle B. Hence the centre of circle A (treat it as centre of mass) must travel the circumference of this fictitious circle (4 units) to reach to its original position. Hence 4 is the answer.

@8Smoker8 4 ай бұрын

"I just put 3 down. I figured that's what they wanted". So depressing if you stop and think about it.

@Magst3r1 3 ай бұрын

That's what the school system teaches you

@p2imal 3 ай бұрын

@@Magst3r1 Which is a good lesson for the real world: Learn to pick your battles. When it's a trivial issue, don't waste your time raising a big stink about any concerns you have. Just do what you're expected to do and move on.

@jholsapple2918 3 ай бұрын

You (as I) initially analyzed from a gear-ratio perspective. The problem is more subtle. (see below addnl comments)

@oching4 2 ай бұрын

life in general is exactly that. on repeat. this is why most nerds who make it are autistic or agreeable or naiive and basic. others get depressed. and society deteriorates.

@johneyon5257 2 ай бұрын

except 3 is a correct answer - the problem that the 3 students who "corrected" the SAT - was that they overthought the question - in fact "revolution" as more than one meaning - and i would have interpreted it the way the questioners intended it - on a flat surface - the rolling coin that starts with the head upright - will have made 1 full rotation/revolution/roll (when the circumference has fully played out) when it's upright again - but put it on a curved surface - and that no longer applies when rolling a quarter around a fixed quarter - the coin has NOT made a full rotation when George's head is upright again at the bottom of the fixed coin - if you mentally straighten out the edge of the fixed coin - you'll realize that the head of the rolling coin is UPSIDE DOWN when it's on a straight line if at the start you placed a dot on the edge of the rolling coin where it was touching the other - that dot would not be touching until it has gone all the way around to the top of the fixed coin

@StefanNoack 5 ай бұрын

You can also arrive at the N+1 solution by considering the case where the radius of circle B is zero. Circle A would not roll at all but still hinge around the point and make one full rotation.

@MiauMichigan 5 ай бұрын

Great idea!

@EduardoGarcia-eh6sh 5 ай бұрын

🤯

@bobhuang94 5 ай бұрын

Or leave circle A and B attached at the same point and rotate circle B clockwise. This is effectively the same as having circle A orbit circle B without any rotation.

@EduardoGarcia-eh6sh 5 ай бұрын

Makes me want to research gears now

@jamesonbornholdt7302 5 ай бұрын

We know...

@justinjames3028 2 ай бұрын

This was fascinating. I would not have caught the error but I imagine there were plenty of others who either thought the answer should have been 4 but didn’t contact the SAT; or thought it was 4 but talked themselves out of it. These three just happened to be both confident enough and motivated to contact the SAT.

@bytecode5834 Ай бұрын

Fantastic video, thanks for sharing you knowledge

@lexxynubbers 5 ай бұрын

In 1976 my maths teacher gave us the 2 (identical) coin problem. She insisted the answer was 1. I got 2 coins out and demonstrated that it was 2, but she could not be persuaded. It seems like this was a common mistake amongst teachers of that era.

@orangenostril 5 ай бұрын

Literally seeing it in front of her and _still_ insisting it's not true is wild

@thehandleiwantedwasntavailable 5 ай бұрын

She sounds like a useless teacher.

@erikthomsen4007 5 ай бұрын

@@orangenostril "Your coins must be faulty. The answer *is* 1. Now go and sit down!"

@bunface 5 ай бұрын

Still true today for many teachers, especially in Asia. Teachers are often drilled to "teach what's correct" but never consider what happens when they are wrong. I've been teaching for the past 10 years and the way I look at teaching is, I don't teach. I share and learn at the same time. I share what I know with my students, and encourage them to seek their own versions of the knowledge, and I feel great when they come back with alternative perspectives to the same subject, or other versions that they've found. Then we explore the differences together. This fosters an atmosphere of collaborative learning and students are much more willing to engage the subject, because they own the learning process. For me, I grow with them.

@olivergottkehaskamp3369 5 ай бұрын

@@bunface 💖

@scottthacker9554 5 ай бұрын

I have a 1st class degree in Physics and clicked on this thinking it would be simple algebra, I had a huge grin on my face whilst being explained to how I was wrong. I love these kind of videos, I love learning something new. Never stop learning!

@theswordofthespiritspeakstoyou 5 ай бұрын

the phenomenon he describes is true, but it does not apply to astronomical observation the way he makes it out to be. According to their own theory, the tilted axis of supposed ball earth always faces into the same direction (towards the star polaris) in this 360 degree orbit which supposedly gives us the seasons. That means the earth is independently rotating ACCORDING TO THEIR OWN THEORY which contradicts this presentation completely because in this presentation earth is dependently revolving around the sun as if there was a mechanical connection between sun and earth, like a carousel, which we know from actual reality that it is not like this.

@josephh891 5 ай бұрын

@@theswordofthespiritspeakstoyou Apart from getting everything wrong, it does apply to astronomical objects. I'm not sure if you're being serious though. A lot of people, people who never had a chance at education (surprise surprise), repeat stuff from other people who pretend that they believe "earth is flat" to make money of such people. I personally find it hard to believe that anyone who older than 5 can believe "earth flat".

@theswordofthespiritspeakstoyou 5 ай бұрын

the typical response of denial or paid actors: personal attack without arguments. You can't even stick with the topic. There is no point in having a conversation with you. Good luck.@@josephh891 btw I am seeing this channel has a few million followers making money off of spreading lies. None of the people I talk to make these amounts of cash! You might want to reconsider your insults, they don't stand the test of time... but then again so does the heliocentric model not

@joelnilsson7129 5 ай бұрын

Yeah, I paused the vidoes calculated and divided the circumference(even did it on a calcluator and made myself realise after getting the answer how unecessary that was) and thougth the answer was obviosu and ez. Then after already calling myself dumb I got even more corrected :) But as U said "Never stop learning"

@joemarshall4226 5 ай бұрын

Flat earth websites are largely a creation of the intelligence community. There are legitimate conspiracy inquiries that point the finger at national and international BIG LIES. So one of the ways of getting people to ignore said theories is to "muddy the water" (a CIA term), by confusing the population. Let me give an example. Suppose the JFK assassination was really a plot...a plot by "deep-state" people who wanted JFK dead because his policies were threatening military or financial goals of the deep state. So you create a very slick "Flat earth" website, in which you also show evidence that JFK was murdered by a conspiracy, and you also mention evidence that 9-11 was an inside job, also designed by the deep state. In this way, people who don't like conspiracy theories will conflate "flat earthers" with JFK conspiracy theorists or 9-11 theorists, and just come up with the conclusion, "Hey, those conspiracy theorists are all nuts." thus ignoring two conspiracy theories that have some merit. Believe it or not, there are propagandists who work full time at this sort of thing. That's why it's called the Information Wars.

@djdoc06 2 күн бұрын

SOLVING ANALYTICALLY: (a) 6 oclock mark on small circle touches the big circle at 3 points (at 12, 4, and 8 oclock on the big clock) while circling the big circle (b) the small circle is oriented upright at FOUR POINTS during its path. First at the top, once between 12 and 4, once between 4 and 8, and once between 8 and 12. Or more specifically at 12, 3, 6, and 9 on the big clock. INTUITION PART: The small circle measures 3 circumferences along a line segment. Then if you curve the line segment to make a 360 degree loop, the small circle would have to make an additional 360 degree revolution to traverse the curved line.

@patrickbateman69420 2 ай бұрын

This really hurt my brain until the whiteboard explanation. Now it's so clear!

@d.bcooper2271 20 күн бұрын

More confusing

@tc6818 3 ай бұрын

10:44 The circle traveling on the outside of the triangle helped me visualize the solution best.

@TinMan-kd2gv 2 ай бұрын

As an engineer, I made the same answer mistake just like anyone else till realized yeah it is the center of the circle ⭕️ which + 1 because it is running outside then yeah it makes sense.

@JB-nf8nk 2 ай бұрын

I knew this was the case because I visualized it immediately, but I still didn't know the answer until he said it increases the distance traveled by exactly one circumference of the circle, then I was ashamed of myself for forgetting curvature introduces an extra rotation. I had learned this during mechanical engineering school and missed my opportunity to say "I know the answer!"

@stix562 2 ай бұрын

The part here is that it's rotating around not with it like gears then they both become flat lines and 3 to 1 ratio. How is that to blow ones mind.

@anirbansingha6723 2 ай бұрын

Yeah

@glennpearson9348 6 ай бұрын

There's been a couple of videos on this particular SAT problem before. I'm an engineer and a bit of a math nerd myself, so I understood the point the other video was trying to make. However, Derek uses both computer graphics and real-world cut-outs to explain things, and that sets this video apart from the others. Very elegant, as always, Derek. Love your vids!

@gruanger 6 ай бұрын

I haven't watched this video yet, but based on the thumbnail, it is one that super annoys me because the answer depends on perspective, how you view the english language. I should go find my comment from the past, but first I should watch the video. I just know I will get annoyed when I do, lol

@Redmenace96 6 ай бұрын

Thank you, for a great YT comment!

@gruanger 6 ай бұрын

haha, good point@@Redmenace96

@Alpha_Online 6 ай бұрын

@@gruangerhave you watched it yet?

@gruanger 6 ай бұрын

Watched it :) The video didn't annoy me but it is the problem I remember@@Alpha_Online

@Neishy4AGTE 2 ай бұрын

I love these sorts of things where you can make it as complicated, or as simple as you like.

@JClayJohnsonOfficial Күн бұрын

What makes it intuitively easiest for me to understand is to think about it this way: if the circumference of Circle B were 0 (i.e., a dot) then rotating Circle A around it would result in one revolution. So any addition to the circumference of Circle B would simply add on to the starting number of 1 rotation needed.

@jonathanbost8427 5 ай бұрын

I paused the video with the question before the multiple choice answers came up. I debated with myself but decided the answer was 1 (because of the term "revolution"). I was disheartened when seeing the choices, deciding it must be 3, and then excited again when you said the answer was not an option. Then disappointed again when you said it was 4, and then excited again when you said 1 was a possible answer . . . a real rollercoaster of a video.

@anainesgonzalez8868 4 ай бұрын

Literally same❤

@vineethbharadwaj8187 4 ай бұрын

Exactly. Rotation and Revolution are pretty different imo. Pretty ambiguous

@chrissherlock1748 4 ай бұрын

Revolutionary comment

@wayneerichsen 3 ай бұрын

That coin rotated once in the first demo, I don't understand how it was 2? With its head up, it went around once before its head was up again.

@vicpnut1 3 ай бұрын

Was mostly with ya till 10mins….then i felt like a toddler afterwards 🤦🏼‍♂️🤷🏼‍♂️😜

@SLCCWebmaster 5 ай бұрын

I've been amazed over the years how vaguely, or just poorly worded, tests questions or assignment questions are in K-12 education. It's also a problem in higher education. When I was in school I was sometimes frustrated at how the teacher who wrote a poorly-worded question seemed incredulous that anyone would misunderstand. Sometimes the problem was that the teacher was unable to account for more creative thinking than their own.

@graup1309 5 ай бұрын

I find it's especially problematic with multiple choice tests. I grew up in a country where they are barely used at all (only for tests that are meant to give an idea of how students as a whole are progressing. They are more meant to test the school and education system as a whole and the grade doesn't account for much) and when I prepared to take the Cambridge Certificate (basically like TOEFL) most of that time was spent learning how to answer multiple choice questions bc well, all important exams we had ever taken up to that point allowed you to explain your answer and what was graded was the whole answer and as long as what you did made sense and was well explained.

@rdizzy1 5 ай бұрын

Not sure about others, but this was really bad for me, as I had major issues taking the problems (as i am autistic) extremely literally with very little wiggle room. To others, it may have been very easy to "tell what they meant", not for me though.

@fragophilefiles9976 5 ай бұрын

But this time it's not about wording it's about a wild paradox!

@Sandman382 5 ай бұрын

@@fragophilefiles9976 And wording. As he stated the wording of the question allowed for 3 different answers two of which and arguably the most relevant answer wasn't an option.

@lesliekerman4222 5 ай бұрын

The most ironic thing is that the testwriters can make questions as ambiguously worded as possible but as soon as you missed a unit or misused one word you lose a point

@dangerprobe1 2 ай бұрын

Another way of solving this could be making a line X, on centre A, parallel to point B and then rotating the circle A with respect to line X, such that line X will be always parallel to point B… it is basically same as solving with respect to point B as you said but I just noticed that while I was observing you demonstrate the question…

@JackDespero 16 күн бұрын

I needed to watch the video twice for the intuition to settle, but I think I finally got it. It is one of those paradoxes that is hard to understand even when you know the answer. Then it does click and it makes total sense. It is so obvious that you are confused as to why you were wrong the first time. The world is fascinating.

@monopolyking879 2 ай бұрын

I am currently 6 weeks from earning a Purdue Aerospace Engineering BS, I have completed the requirements for a physics minor, ive taken 2 graduate level astronomy courses and a graduate level Space Traffic Management course that dealt with sidereal time on every assignment, but this is easily the best conceptual explanation of sidereal time I have ever seen. Genuinely incredible educational content, I'm blown away.

@magnuslarsson337 2 ай бұрын

Hear, hear!

@Worms_Pro 2 ай бұрын

Keep It Simple Stupid KISS

@The_E_Lord 2 ай бұрын

Damn I wish to do aerospace/astrophysics too

@rose_allen 2 ай бұрын

Out of curiousity, how often do people pronounce it side real and how often do you hear cider eel? I'd seen the word before and assumed it was a compound word - and Astrophysicists seem like exactly the kind of people to read a word and understand its meaning before hearing it out loud.

@tmst2199 2 ай бұрын

@@rose_allen You're hilarious.

@AndrewMoizer 2 ай бұрын

I figured 4 right away: 3 turns for the gear ratio, and one more because the small gear is going around the circumference. Then spent half an hour trying to figure out why I was 'wrong'. Even dug out old Meccano gears to confirm I was not mistaken (which let me confirm 2 for a 1:1 ratio, 3 for a 2:1 ratio, and 4 for 3:1. And then I watched the rest of the video and learned a few other things that made it all worth while. Thanks.

@mistrants2745 Күн бұрын

at 5:30 i literally said out loud "this is a glitch in reality, this makes zero logical sense". Then at 5:35 i suddenly got it. The smaller circle is taking a path that isnt 'just' the path laid out by the circumference of the larger circle. Its following a path thats the circumference of a circle with the diameter of the larger and the smaller circle put together.

@paparmar 5 ай бұрын

I'll always remember when in my freshman astronomy lab, we directly measured the sideral period of the earth. The rooftop-dome telescope was aimed at a patch of sky with it's tracking motor turned off. Over the course about 20 minutes, each of us would peer through the eyepiece (no computer screens back then) and pick out a star that came into view, quickly making a sketch of it amongst its neighbors. When our chosen star passed behind the crosshair (we made sure no one rotated the eyepiece) we each started our stopwatch. Once everyone had their turn, we labelled each of our watches and put them in a cabinet. Then next night we all returned, and one-by-one, observed our star slide across the view, and stopped our stopwatch when it again went behind the crosshair. Mine read 23 hrs, 56 min, 3.92 sec. Across the class, we were all within a quarter second of the actual value. Yes, really simple (and dependent on there being two clear nights in a row), but how many people can say they've done that?

@johnwilson1094 5 ай бұрын

Yes! Sidereal time! Thanks

@gabrielgonzalez1993 5 ай бұрын

Beautiful

@ohyou_6599 5 ай бұрын

me, I've done that with timelapses over 24 hours. really cool stuff.

@jaelwyn 5 ай бұрын

More schools should do this, and similar experiments that require minimal outlay but reconfirm "known" results. For example, I would expect most schools to be able to find someone due north/south who could set up a vertical pole and measure the length of the shadow at solar noon on a specific day. Which, with some trig, is all you need to confirm that the Earth is curved (at least along a north/ south path), and the circumference (if you assume a sphere).

@xDXD-xo2qi 4 ай бұрын

wow ur ancient, did u shake hands with trexes back in the day?

@ElectroBOOM 5 ай бұрын

This was a great video! Blew my mind when I realized how I was wrong!! Good to know question wordings can be so important, eh?! 😁😉

@ThapeloMKT 5 ай бұрын

I was confident that I was right, but because of that, I was then confident I was wrong

@iamdigory 5 ай бұрын

I'm just glad I got the correct wrong answer

@ninthjeans3749 5 ай бұрын

same

@michaelharrison1093 5 ай бұрын

Are you familiar with Symmetrical Sequence Component theory created by Charles Fortescue in 1928? In this work he proves why 3n+1 harmonics are positive sequence (rotate in the same direction as the fundamental) and why 3n-1 harmonics are negative sequence. This comes down to this very coin paradox problem

@stephensirait5146 5 ай бұрын

what was you trying to imply here bro 🤣

@mattc2626 5 күн бұрын

10:49 This image really helped everything click for me. When the circle goes around a corner it rotates but doesn’t cover any linear distance on the surface of the triangle.

@indigoriviera 2 ай бұрын

Fantastic explanation! You are one of the clearest and most creative instructors on KZfaq. Thank you for your content.

@Schweebcraft 6 ай бұрын

As a machinist, we deal with this quite a lot. When milling around a circular boss, you have to do a calculation how much you need to increase the feedrate to keep the same speed at the outside of the end mill. The same goes for milling inside a hole, except you calculate the smaller diameter caused by the size of the tool instead, since everything is based on the center of a circular tool.

@mitchelljao 6 ай бұрын

Super interesting!

@appa609 6 ай бұрын

Dude how fast are your feeds for this to matter?

@fresheFresse 6 ай бұрын

@@appa609 On a production machine this matters. For one offs who cares.

@devjk1 6 ай бұрын

As a CNC programmer, that's not really true. I just asked a couple other programmers/machinists at my shop this question and nobody got it right. The thing you have to deal with is varying chip load, which isn't the same at all.

@wingracer1614 6 ай бұрын

@@fresheFresse Yeah doesn't matter at all for one offs and low volume stuff. When you need a machine running 24/7 for years to make 12 million of something, a fraction of a second quicker could save days

@berryl9653 6 ай бұрын

Undergraduate astronomy student here. The idea of solar vs sidereal time was something I had heard about before, but never properly understood until now. Thank you for all that you do!

@temple69 6 ай бұрын

I still don’t understand exactly how the movement of the earth affects the rotation time.

@patrickchang9135 6 ай бұрын

@@temple69 Watch a 3D demonstration of it

@igarazha 6 ай бұрын

But why should we add 1 day for Sidereal year, if Earth may not "slipping"? But it was correct only for slipping case

@duzyolek 6 ай бұрын

@@igarazhaQuite the opposite. It works only if there is no slipping. Which is exactly the case with the Earth's movement around the Sun.

@AwesomeHairo 6 ай бұрын

Thanks for not misusing any comma.

@johnnyshell2839 Ай бұрын

The explanation you gave just showed your point. Pov determines internal and external proportion. +1 and -1

@N65-sim Ай бұрын

I thought I was wrong when I came up with 4 as answer, but later realized it wasn't in the choices. Reason I came up with 4 is because we're basically calculating the displacement traveled by a rolling circle, and the distance traveled by the center of the small circle is the same as displacement done by any point you pick on its circumference 😆

@nico2006t 13 күн бұрын

Excatly

@foxboy6662 4 ай бұрын

As an aerospace engineer, once I realized this is sort of a trick question, I visualized it as I do with sidereal and solar days. I'm happy you talked about those in the video.

@basildraws 4 ай бұрын

Same thought. How is it possible that not one of the test writers/editors etc. had even the most rudimentary understanding of astronomy? I solved it from the thumbnail, before watching the video and wondered how I could be wrong, since my answer wasn't listed.

@jeffmartin-g8r 3 ай бұрын

I wish Derek had rolled his coins in the other direction to match solar system's rotation. My head is stuck on the astronomical visual (and I have a hard time dropping that out of my head).

@dvelarde 3 ай бұрын

ABSOLUTELY NOT A TRICK QUESTION. Saw the answer just by looking at the problem, only to watch the video and see that I was correct. The problem with average minds is that when they become highly educated, the tend to Believe that they are way more intelligent than they really are, when in all actually they are just smarter than than rest of us.......... in one specific area.

@hamasmillitant1 3 ай бұрын

@@basildraws it was a trick question they told u it made 1 revolution then they asked u howmany revolutions it made if ppl misread question and answered how many rotations it made well thats like being asked if 2 trains are traveling at x speed and start from station x & y at time x when will they meet and deciding to submit a answer on wind speeds over tracks instead

@basildraws 3 ай бұрын

@@hamasmillitant1 No, it wasn't a trick question. If it had been, then "1" would have been on the list of choices. So even if they HAD intended it that way, they still made a mistake. It's pretty clear they meant for the student to calculate rotations based on the choices given, and it's clear they still failed to calculate the answer correctly themselves. The use of the word 'revolution' instead of 'rotation' is just an ADDED mistake on their part.

@sarthak-ti 6 ай бұрын

It’s so impressive how you made this seemingly basic math question into a really interesting and well thought out video. I hadn’t even considered the idea of a Siderial day, it’s so cool!

@aleksitjvladica. 6 ай бұрын

Thou ne maketh a full point, anything of mathematics must be really interesting.

@andrewrhsmith 5 ай бұрын

Agreed

@bill5197 5 ай бұрын

@@aniketmeshram6598 reconstruct your sentence. Please.

@aniketmeshram6598 5 ай бұрын

@@bill5197 i mean to say that he/she/pronouns wants to defy this Cosmic phenomena which was discovered by that great mathematician and astronomer who gave us "Zero"

@jessicapeyton5444 2 ай бұрын

If the big circle had paint on its perimeter and the rotating circle was getting painted as its edge touched the painted portion, there would be a blank space (with no paint) when the smaller circle is right side up (4:30). To paint the whole circumference of the small circle, you would need to go a little further which would reach 1/3 of the big circle. So even though the small circle has "rotated" 4 times, it has not matched up with the circumference of the big circle.

@hydropage2855 Ай бұрын

To me it was actually intuitive that it should be 4. Think about it, the circumference of the smaller circle travels as much as ITS CENTER around the larger one. The distance the center of the smaller circle travels is really a circumference of radius (1 + 1/3) times the larger one: 4/3 the radius of the larger circle. Divide this 4/3 by 1/3 to get how many times the smaller circle’s circumference wraps around THIS “true travel circumference”, and this is 4. (Edit: I watched the rest of the video, turns out my intuition was exactly what was explained in the video haha)

@Mr.MoonRabbit 5 ай бұрын

There is an anecdote of a professor in the math department of the university I went, who wrote in a final exam of calculus something like "do you dare to calculate the sum of the series?" to which a student answered "No". The professor said he had to give the student full marks since the answer wasn't wrong, and he started being veeery careful in the wording of the exams

@bvenable78 5 ай бұрын

That happened to my junior year English teach in high school (but a year before I took her class). The exam question was "describe the book 'The Scarlet Letter'". As I'm sure you've already guessed, one student wrote a 5 paragraph essay about the size and shape of the book, the various artistic properties of the cover art, the texture of the paper and the font used, etc. According to her, she took it to a faculty meeting for help, and the other teachers concluded that she had to grade it as a correct answer.

@mleszzor6866 5 ай бұрын

Both of your stories are amazing!

@raygordonteacheschess5501 5 ай бұрын

once I wrote a paper for a friend who said "I didn't know anything about the breakup of the soviet union, so I asked a friend, and HE said: " then she put my entire paper in quotes, ending with "I couldn't have said it better myself." She got an A.

@kev4241 5 ай бұрын

can't get hung up on small quibbles, quickly scrawl the "F" and move on

@josephkavanagh7815 5 ай бұрын

I took a 3rd year math course called numerical analysis. We had to "Prove a theorem" on an exam that involved a set of given variables in relation to the error when solving differential equations numerically. The intent of the question was to basically memorize a theorem about the minimum error produced we proved in class and reproduce it on the exam. Except the question said nothing about proving a minimum - it just said prove A theorem. I thought I had understood the process of the theorem so I didn't have to memorize it, but I just couldn't get it to work out to show a minimum. I ended up proving a maximum to the error which was correct (we did not do this in class), and he had to give me full marks as he didn't specify which theorem to prove. I ended up with 100% on the exam, and he learned to more carefully word his questions!

@daleferrier3050 5 ай бұрын

I’m glad you chose 3 at first. I didn’t feel so stupid because of it. 😂 The triangle shape was what helped it click with me. When the circle is going around one of the corners, the point it touches the triangle doesn’t move, but the circle rotates by a third before carrying on. Third multiplied by 3 corners equals 1 extra rotation.

@gardenjoy5223 5 ай бұрын

Did you even watch the video? Did you miss, that it is always just +1? So 365,24 days of rotation about the sun becomes 366,24 from a different view point? +1 exactly even there.

@MeMe-gm9di 5 ай бұрын

Yeah, that makes it a lot more intuitive for me as well. Especially since you can easily in your head generalise it to rectangles, pentagons, hexagons, … So the circle intuitively follows.

@the1doubledeuce 5 ай бұрын

@@gardenjoy5223 I mean, he saw the whole triangle part, didn't he? The concept is not the easiest to fully grasp, and I also agree that the triangle part helped to make it make sense to me, a simpleton.

@chronoreverse 5 ай бұрын

I thought 3 immediately, backtracked because it had to be a tricky question if it were on Veritasium, recalculated 4, didn't see it on the list and decided to just watch the rest of the video.

@Cotronixco 5 ай бұрын

No, not 1/3 at each corner. Less than that.

@annimon2814 Ай бұрын

By far the coolest KZfaq video I’ve see in a while

@bengarrett4984 7 күн бұрын

Thank you for including the practical application of this math problem. One of the most frustrating part of my education was asking the teacher why I needed to know something and getting the answer "because I said so".

@Burnoff_ 6 күн бұрын

That's why you don't study in American schools lol

@davidfehrle8561 5 ай бұрын

I had an error on my SAT too (in 2016). Half of the exams had a misprint that switched the time allowed for each section with another section. They ended up throwing away both entire sections of the exam, I was pretty mad since it was parts in my strongest subject getting tossed. Timing is a big part of the SAT and I feel bad for folks who may have spent longer on this problem since the real answer wasn’t listed which may have cost them more than just the one free point in the end.

@samgray4 5 ай бұрын

This is why skipping questions you can’t immediately solve is such an important standardized test strategy

@PANDEAD2 5 ай бұрын

If someone was dumb enough to continue wasting time on one question that was stumping them instead of moving on and finishing everything else and returning, I doubt it made much of a difference to their end score.

@Boltclick 5 ай бұрын

@@PANDEAD2 That's not necessarily true. Some questions require more time, so a person might just assume this is a harder question. Thus, instead of spending their normal 1 min, they'll spend 3 minutes. Generally, the skipping questions when you're stumped is good if you don't know where to start or if you think the problem will take too long, but otherwise, spending an extra couple of minutes is usually worth it, as otherwise you'll just lose your train of thought if you skip the question. Since the question had a misprint, it's entirely possible that some people had the right idea, and were sure they knew how to solve the question, so they spent that extra bit of time to hopefully solve the question, instead of completely discarding their train of thought for that problem and moving on (since moving on effectively resets their progress on that question to 0).

@Techburn997 5 ай бұрын

@@Boltclick Skipping then returning tends to be the better option as there may be later questions with similar reasoning that will simplify the harder question. It also allows you to divvy up your remaining time more equitably between any other questions skipped.

@gabbleratchet1890 5 ай бұрын

It’s also a good strategy because you are penalized for wrong answers but not for blank answers.

@LOCOBJORN 5 ай бұрын

What’s crazy to me is when I tried to solve it, I intuitively did one rotation of the little one on the big one in my imagination and saw it only go a 1/4 of the way. I then thought to myself, “wait that must be wrong”. Mind blown

@Genesis-revelation70 5 ай бұрын

I did the same thing and guessed 9/2 since it was the closest answer haha

@Mandragara 5 ай бұрын

I snipped the small circle into a string and draped it over the larger circle in my mind, giving me the answer of 3

@oneilljames1 5 ай бұрын

Yea but it's just a visual representation of the problem, you're supposed to use the data given in the problem. The actual size of the "coins" in the image is meaningless

@Mandragara 5 ай бұрын

@@oneilljames1 The image is to scale

@ADUAquascaping 5 ай бұрын

Use cosine and sine. Set the edge as cosine (0,1) and the center as sine (0,0). 2 Pi is one cosine rotation. 2 Pi is two sine rotations. Cosine as the circumference has four 90-degree rotations and sine as the vertex has eight 90-degree rotations within 2 Pi.

@tomoakhill8825 Ай бұрын

Starting in 1967 and continuing through 1974 I took the SAT 4 times: "practice", "merit scholarship", college entrance exam, and, 5-years-later, another college entrance exam when I finally went to college. My low score on the math section was 792 out of 800, I got an 800 twice. Every single SAT TEST I had to figure out what _wrong_ answer (2:35) the test writers wanted on multiple questions. Obviously I was good at deducing the "correct" wrong answer. Remember they are testing people like Dr. Doug Jungreis, and me (I have a physics Ph.D. from Harvard). But no one with our skill set works for the College Board writing tests, and only 1 in 1000 students scores as high as we did.

@plektosgaming Күн бұрын

Praxis tests are like this as well. Multiple wrong answers and having to figure out what they thought was "correct". It looks like they have lifted old SAT questions and dropped them in. Really sad when you consider that this is the exam that is required of K-12 teachers in many states.

@user-bt8mh1it2h 2 ай бұрын

What an awesome video,full of knowledge and images, lots of explanations,very good job😊

@R_gue 5 ай бұрын

I really liked the graphic when Jungreis was explaining his proof at 9:49. The additional +1 radius from the smaller circle added to the larger circle is super clever. Awesome video

@M4TCH3SM4L0N3 5 ай бұрын

Geometry is the best mathematics, and I will never be convinced otherwise.

@ADUAquascaping 5 ай бұрын

@@M4TCH3SM4L0N3Instead of adding +1, you can allow the vertex to follow sine or cosine and the circumference to follow sine or cosine. Circumference measurement is one rotation for 2 Pi and vertex measurement is two rotations for 2 Pi. You're just changing the path and starting point of the measurement. He used trigonometry, and could have just kept using it for his proof.

@M4TCH3SM4L0N3 5 ай бұрын

@@ADUAquascaping I understand that you CAN use trigonometry for the proof, and I'm not saying that isn't valuable; I'm simply saying that I prefer the branch of mathematics that only requires a straight-edge and compass and its corresponding axioms and proofs.

@ahall9839 5 ай бұрын

@@RepentandbelieveinJesusChrist5 Sad how religion turns you into a mindless drone

@CF542 6 ай бұрын

The fact that the main issue was a poorly worded question is the exact issue I've had in school with so many tests being poorly written. So often the test writer(s) understand the questions they wrote but they don't have them vetted properly so they can be understood by the test takers.

@jaakkopontinen 6 ай бұрын

This so very, very much. The countless pains of trying to figure out whether to answer what's literally being asked instead of answering what would seem to be what the maker of the question wanted to ask. It's ridiculous how such a thing exists so pluralously in tests, questionnaires, forms and medical examination papers etc.

@silentdrew7636 6 ай бұрын

I don't think the question writer knows what a revolution is.

@tristanpage9548 6 ай бұрын

Well I guess if anything it better prepares you for life

@reefhog 6 ай бұрын

That’s not a fact. The main issue, is that the correct answer wasn’t even there. The wording of the question was poor also.

@bkucenski 6 ай бұрын

Math word problems are more often English problems which is why they are often criticized as being racist. You shouldn't need to be an English major to sold word problems. They should be written like people naturally speak. And the answer should reflect that as well.

@joeterp5615 2 ай бұрын

This got my mind really spinning! 😉 So I did my own little experiment, but using rectangles. I found the number of rotations for same-sized rectangles is the same as for the same-sized sized circles (i.e., the quarters) shown in the video. I used a couple Chipotle napkins that were sitting next to me on the couch lol. The outer napkin rotated 2 full times to get back to the original location. And sure enough, when I figured out how to alter my perspective to that of the inner napkin, there was only rotation from that perspective. This was a fun simple way to reinforce a key principle in this video.

@garvitahuja3717 28 күн бұрын

It can be done using concept of rolling in physics Let velocity of centre of smaller circle be v, radius of bigger circle be r, angular velocity of smaller circle be w, no. of revolutions of smaller circle be n Now, the centre of smakler circle is revolving in a circle of radius r+r/3=4r/3 about the centre of larger circle So, time for 1 revolution will be 2π×(4r/3) / v = 8πr/3v =t (let) Since smaller circle is in pure rolling motion, velocity of point of contact with larger circle is 0 So, v=w×r/3 , so w=3v/r So, 2π×n/w = t So, n=wt/2π = 4

@4RILDIGITAL 5 ай бұрын

Three of them got it right by saying that the question was wrong.

@wqters5772 5 ай бұрын

likebot more

@prashantmishra9985 5 ай бұрын

1k likes within 5 minutes? Wow!

@EzraHaviland 5 ай бұрын

Also 3 is still a correct answer to the problem it’s just badly worded. So everyone who answered 3 still got it right.

@stevejones1318 5 ай бұрын

The question is incomplete. It should ask how many rotations does the small circle make, on its centre point, to rotate exactly once around the large circle.

@rfvtgbzhn 5 ай бұрын

@@stevejones1318they forget an A. If there was one more A in the question, it would be correct.

@jasonpatterson8091 5 ай бұрын

Watched this with a friend and they really struggled with the extra rotation per revolution until I showed them a coin rolling along the edge of a rectangle. It's getting around the corners that causes the additional rotation - angular movement is required without any linear movement. The circle is just the limit with an infinite number of infinitely small corners. On the inside of the circle (or any concave corner) that corner rotation is in the opposite direction, so in one loop of any size and shape it will result in -1 rotation.

@MiauMichigan 5 ай бұрын

Thank you!!! I finally understand 😊

@Warfred 5 ай бұрын

Actually get it now!

@mk1cortinatony395 5 ай бұрын

that made it easier for me thanks. Pity the guy doing the vid couldnt explain as easily.

@stephenwatkins7592 5 ай бұрын

@@mk1cortinatony395 He showed how the rounded path around the corners of the triangle could be pasted together to get a complete circle.

@leif1075 5 ай бұрын

What dontou mean on inside lf circle the rotation is in the opposite dorection..the circle.rptsripnal.direction doesn't change so notnsure what you meant..and how does a circle have infinite number of corners..you mean because it has an infinite number pf tangent lines?

@jeremysteinmeier1701 15 күн бұрын

The more intuitive solution is when the head is facing up again (1 rotation), the edge of the coin hasn't actuality traveled the full distance of the circumference. The circle path adds a rotation to the required 3.

@AndyNocturne 2 ай бұрын

My initial response was also 1. Not just because of the word "revolution" but the fact that it's asking how many revolutions until the center point returns to its starting location. Also, it says that circle A "rolls around" circle B. At first, for me at least, that didn't tell me that the circle was necessarily spinning as it rolled around the other. But I guess looking back now, that's what the test wants us to believe the word "roll" means. The whole time I was looking at it, I was imagining the circle just moving around the other without either of the orientations moving. But he said it best, it's amazing how poorly this question was worded lol.

@shardrajput1709 2 ай бұрын

bro it is 9th standard question why explaining so much

@peter9477 3 ай бұрын

My brain didn't fully accept this until I pictured a circle going "around" a straight line segment in the same manner. Picture a horizontal line segment, circle positioned above it at the left end, bottom (not right or left side) of circle touching the end of the line segment. The circle travels to the right along the length of the line. Then to flip itself around the right tip of the line to the bottom side it has to undergo a 180 degree turn, but while doing so it travels no additional distance along the line. (Its centre travels a distance along a semicircle, but the part touching the tip of the line does not.) Then back along the bottom of the line to the left, then another 180 degree rotation back around the left tip, to the top again. Total distance traveled is just twice the length of the line. Number of rotations is some amount to accomplish that traveling, PLUS one additional complete rotation. Same thing for any convex shape that it travels completely around.

@peter9477 3 ай бұрын

I hadn't watched this far when I wrote that, but he almost describes this at @11:15, though for some reason he stops after only one side of the line.

@x0rn312 3 ай бұрын

This is a good explanation.

@marissabulso6439 3 ай бұрын

Thank you, that really helped put the broken pieces of my brain back together. 😂 Much appreciated. ❤

@k.r.koushik9660 3 ай бұрын

Thank you so much. Was going mad

@codyhall6802 3 ай бұрын

Great explanation thanks

@PramodApte23 5 ай бұрын

The best thing about Veritasium videos are that they keep giving. The video could have been ended at multiple occasions, but they make an amazing, extensive learning out of it.

@Leyrann 5 ай бұрын

I'm really glad Veritasium included the astronomical part. The moment I realized my mistake (which happened when I gave it some more thought after he confirmed that 3 was wrong), I noticed the connection to sidereal days - as a kid, I spent ages wondering why my astronomy books claimed a day was only 23 h 56 minutes long, so that's pretty firmly imprinted on my mind.

@nameredacted1242 5 ай бұрын

Leave it to Veritasium to make a 45-minute fascinating video on a seemingly trivial topic!

@louiejohncastillo9822 5 ай бұрын

I think the explanation here is confusing, its actually pretty simple if we use SUPERPOSITION: take the number of rotation ("revolution" along the circumference flatted out as a line) we call it "linear". and the number of the revolution of center point of circle A along the circumference from start to end (the given is 1). to be less confusing, lets just say the single revolution of the circle A, along B. we call it "given". linear = 3 given = 1 total = 4 this is true for all radii. ex. 2: for 2 coins of the same radius for about 1 revolution. linear = 1 given = 1 total = 2

@theboxingbiker 5 ай бұрын

If you learn real math go to mathologer. Veritasium is rookie compared to him

@ChopeZzz 4 күн бұрын

So complicated explanations. Here's a simple one: If we use a large circle length as a straight line, the small circle will rotate 3 times. But since the line is not straight, but curled in a circle, this adds another rotation to the small circle, resulting in 4. Love the video 😎👍

@jaydubb01 2 күн бұрын

He says that at 4:53

@ChopeZzz 2 күн бұрын

@@jaydubb01I know, I am talking about some of the commentators, they are overcomplicating the simple 😁

@MrNikhilkecian 15 сағат бұрын

in my native language you nailed it bro that's made my subscribing your channel meaningful can't appreciate you enough

@pradeepkrishnamurthy2557 5 ай бұрын

That actually blew my mind. It was so great to see how a simple math question with two circles can be related to space observation. Thank you for such a great content!!

@DavidEdwards9801 4 ай бұрын

Wait till they figure out how it ties in to space travel too =)

@reidakted4416 6 ай бұрын

One of my SAT questions (on the verbal test) still bothers me. It was the analogy questions "A is to B as X is to . . . " and they were asking for the meaning of "sanction" and both "to approve" and "to punish" were options. I wonder who sanctioned that and if they were sanctioned. 😆

@Dont_Read_My_Picture 6 ай бұрын

Don't read my name

@fredrickcampbell8198 6 ай бұрын

My goodness.

@lw8882 6 ай бұрын

or sectioned

@MisterItchy 6 ай бұрын

This could be valid. I assume 'sanction' is the 'X' in the above. We would have to know what the A is to B part is.

@ToaAsum 6 ай бұрын

Autoantonym

@kibnob Ай бұрын

I got the answer using the center-distance proof right off the bat!! Thanks for the self esteem boost, really needed that today

@SchawjibbWanders Ай бұрын

I am 40 now. My father told me about sidereal year concept when I was 9 or 10. I just didn't believe him then; I thought he might have made that up to add another day in a year! This video made me nostalgic and, as by product, helped me understand the concept.

@ChadThundeclock 6 ай бұрын

I think the most intuitive way to understand this is to imagine the inner circle is just a point. Even though there is no circumference, the outer circle would still have to rotate once to go around it.

@pamtam1 6 ай бұрын

👌

@NumbToons 6 ай бұрын

bro. this is amazing,thank you

@T33K3SS3LCH3N 6 ай бұрын

That's one way to see it. Another is to try it with two equal rolls of ducttape. As you unwind the outer one around the inner, you will notice that the point of contact only travels at half the speed of the center of the outer roll. If you start from 12 o'clock and roll it clockwise down to 6 o'clock, the outer roll has done a full revolution around its own center. But it has only unwinded half of its circumference, because the point of contact has rotated _in the opposite direction_ at half of the speed - it went from 6 o'clock over 9 o'clock to 12 o'clock of the moving roll of tape. So the actual length of unwinded tape at this point is 1x the circumference (for the whole rotation of the outer tape) minus 1/2x the circumference, for the counter-rotation of the point of contact. So 1/2 the circumference for 1/2 revolution, even though the outer tape has spun a whole 1x around its own axis. But if you imagined the outer roll of tape to be made out of super-thin tape and be infinitenessimally small, then this counter-rotation would make up practically 0 distance. Like if it only has 1/100 the circumference of the inner one, then it only needs 101 revolutions, so only 1% more than if the counter-rotation was no factor at all.

@rmsgrey 6 ай бұрын

Yeah, I was surprised they didn't include that example.

@phelan8385 5 ай бұрын

Yeah good way to visualize it

@TimeBucks 5 ай бұрын

I can't believe how well the explanation is made.

@user-om1tu8ur3m 5 ай бұрын

Good

@BHUBANSINHA 5 ай бұрын

Fggg

@user-vp9hk4jk3i 5 ай бұрын

Very good

@facundomartinify 20 күн бұрын

This has to be the best channel on KZfaq

@mikeroll8515 2 ай бұрын

Fantastic analysis...great video!

@sudokode 6 ай бұрын

I love how Derek goes the extra mile and tracks down one of the people that called the problem out, who just so happens to be a mathematician now 😂

@jasonkilley 6 ай бұрын

Right?! As soon as I saw his title, I was like, ok that checks out lol

@erikaz1590 6 ай бұрын

At this point, I just assume Derek has a 'Sherlock Holmes'-esque filing cabinet of every mathematician, professor, and scientist he can call on for collabs XD

@abrarhameem8424 6 ай бұрын

matched so perfectly, like a well written script from a movie😂

@thegrizzly7402 6 ай бұрын

is it really a coincidence that the person who called out the test creators on a math problem is a mathematicion

@MrPruske 6 ай бұрын

Always has been

@JinalDoshi91 5 ай бұрын

The simplest way to look at it it is, if you look at the center of circle A revolving around the center of circle B, then in the circular path, the center of circle A has to travel (3R + R) distance, while in a straight line, the center of circle A only has to travel 3R distance. Interesting problem that I have never come across before. This was an amazing explanation on the paradox!

@Bot28111 5 ай бұрын

That’s literally what he explained in the video.

@ADUAquascaping 5 ай бұрын

@@Bot28111Instead of adding +1, you can allow the vertex to follow sine or cosine and the circumference to follow sine or cosine. Circumference measurement is one rotation for 2 Pi and vertex measurement is two rotations for 2 Pi. You're just changing the path and starting point of the measurement. He used trigonometry, and could have just kept using it for his proof.

@balzi76 5 ай бұрын

You keep saying paradox. I do not think it means what you think it means

@AtagoSKK 5 ай бұрын

@@Bot28111He saved us 15 minutes though

@artificialdeathh 5 ай бұрын

I think the simplest visually is: we know the point on A that starts tangent to B will touch it again 1/3 of the way around. at that point A will be on the top right of B, and the point will be aiming down and to the left 120°, an extra 1/3 rotation. So, every time A travels its perimeter, it does 1 and 1/3 rotations, which it does 3 times.

@HughEMC Ай бұрын

Amazing paradox😮 I mean the fact you can turn a straight line into a circle & observing the circles rotation from different perspectives changes the amount of rotations the outer circle makes in both cases. The reality of physics is awesome

@jakemccoy 2 күн бұрын

An easy way to remember how to solve this problem to look at how far the center of the small circle travels. In this case, the center travels 2x4pi. Since the circumference of the small circle is 2x1pi, the small circle must make 4 rotations to cover the distance traveled. You can use the same method to calculate the rotations if the small circle were inside the big circle.

@marcellosmusic7597 5 ай бұрын

Another way to visualize the extra rotation is by making the inner circle infinitely small. The outer circle will still take one revolution to go around. Just use a pin as the inner circle and it will take roughly one revolution for a coin to go around.

@cristian1092 5 ай бұрын

Brilliant!

@bluegold21 5 ай бұрын

Pls, tell me if I am wrong so I know I understand this. I think the pin would still give it an N+ number. You wouldn't use an infinitely small point either. Just an imaginary zero point where there is no there only then can you create a perfect N number.

@Cecilia-ky3uw 5 ай бұрын

I half understand on an intuition level what's going on. The amount of rotations are relative to the plane so three is technically correct from the pov of the line circumference. Sorry Mr Doug, don't understand your previous point about velocities. Also the triangle aroused something in me and I thought of another way to explain it, this only works in shapes with no depressions, but more or less the angle of a triangle's outside is always 360, but you could very well also talk of a circle having a total angle(outer that is) of 360, as weird as that may sound. Although if we're thinking of curves as angles, that may be another way to solve it.

@vincentv.9729 5 ай бұрын

Thx Marcello it totally makes sense this way. If the edge of the circle turns around an axis, il would make 1 x 360° circular distance and 0 x linear distance (the axis is consider a point), hence 0 + 1 = 1 rotation.

@user-kb2in7qb6z 5 ай бұрын

There is no extra rotation of A, it is an illusion because you are viewing it from your frame of reference. Though I like your example, the reality is that if you make the inner circle infinitely small then the thing you are actually moving around that point is the frame of reference of A(ie the axis of A is doing a 360 or full rotation around that point). That point will not traverse one iota along the circumference of A and therefore A will not rotate at all. The thing rotating will be A's frame of reference relative to us and more aptly it's axis. Essentially you would be rotating circle A about a point on it's circumference. A itself will not be rotating at all about it's own axis. A better way to look at it wrt the original question in the video would be to understand that by the time A makes a full revolution/rotation about it's own axis the axis of A itself will have rotated 120 degrees. By the time it makes 3 revolutions as it moves around B the axis of A will rotate 360 degrees which is where the extra PERCIEVED rotation comes from. In actual fact A has ONLY made 3 rotations about it's own axis plus the axis making 1 full rotation makes it look to an independent observer that circle A has made 4 revolutions. Strictly speaking the revolutions are 3. The three students are wrong, the answer is indeed 3. For the answer to be 4 the question would have to have been framed differently: How many revolutions does circle A appear to have made to an observer in an independent frame of reference. For the answer to be 1 the question would have to be framed: How many revolutions of A around B.... As it is framed "How many revolutions of A..." implies revolutions about it's own axis and the only answer to that is 3(ie divide circumference of B by circumference of A). In fact ANY shape would produce that singular extra rotation of the axis of A around the shape(360 degrees rotation) giving the perception of the +1. Note: In astronomy a revolution about one's own axis is called a rotation. This is in order to distinguish it from a revolution around another object or point. However this is an SAT Math question not an astronomy question. There is no expectation that students know or incorporate that into their interpretation of the question while if a revolution of object A about object B in implied then object B is named. If object B not named then the implication is that object A is revolving about itself or rotating about it's own axis to be precise.

@user-kb6mj7zq8t 3 ай бұрын

What is so interesting about your videos is that almost 100% of the I couldn't care less about the topic. Yet, I'm still enthralled through the whole thing. That is most definitely a compliment just to be clear. I love that you love to teach. That's all that matters.

@curiaregis9479 2 ай бұрын

Veritasium is ridiculously talented at making videos.

@tombiby5892 2 ай бұрын

How many sidereal minutes does KZfaq take?

@literallyjustgrass 2 ай бұрын

@@tombiby5892I have no idea but for a production like this it's not uncommon to have multiple hours of side reel just in case

@cbwavy 28 күн бұрын

I definitely have to watch this at least one more time to really grasp how the perspective of the circle's center causes a differet answer than if viewed from a distance outside the circle

@lcloutier1000 Ай бұрын

This is exactly why I have hated every multiple choice exam while at Uni. Which means almost every test. I paused the clip to doodle my way to an answer, saw the circumference ratio as 3, then examined the wording and thought "revolution" kind of means 1, then focused on the path travelled to get back to the "starting point" which meant the r/3+r circle, then got confused about wtf they were actually asking and gave up. Multiple choice tests are only as good as those who write them.

@HuntingSunder 6 ай бұрын

I can say from experience, pointing out flaws in a test is such a double edged sword. I pointed out 3 bad questions on a science test in 7th grade, and the entire class hated me because "I" messed up their scores.

@BlueProphet7 6 ай бұрын

A good teacher will give everyone credit for a bad question, right or wrong. Or AT LEAST nullify it, which could hurt a score if you were 'right' I suppose.

@SenneMeuleman 6 ай бұрын

bro why do you even do that in 7th grade... of course people are gonna hate you when you pull such nerd behaviour... What makes it worse is that even though the questions were bad you could probably answer them 'correctly'

@HHalcyon 6 ай бұрын

@@SenneMeuleman What "nerd behaviour" are you talking about? You can't have errors like that when it comes to numbers. It is correct to point out such errors because it could be a life or death sentence in a world of numbers. These things must be correct. The teacher messed up there and it's nothing to do with "nerd behaviour". At least that mistake was in a classroom.

6 ай бұрын

@@BlueProphet7 Yes, otherwise, it is unfair. The goal of a test is to measure learning, but some students think the test is the goal by itself. (I am a teacher)

@SenneMeuleman 6 ай бұрын

@@HHalcyon mannn, in 2 years i'm done studying and can become a math teacher, do you think i will always make correct questions? Naaaaah impossible, but if its just a stupid test and the desired answer is pretty clear, even though wrong... then what is the problem? And if it really is a problem i would just give everyone a point for that question so no one can complain