In summer 1983 Grand Master Chang Tung-sheng , the Flying Butterfly invited by Dr. Weng to produce Text video tape for Tai Chi course at the Ohio State University. In both level I and II ( 3 credit units) he demonstrated his Chang's Style Tai Chi form and training drills ( stances, postures, force releasing techniques and Join Hands Operations patterns.) . These are all classic precious Kungfu learning materials)