Refraction: Reappearing Coin Trick -Group Activity

I used this as one station in a ‘Waves Circus’ to review what students had learned about waves - in this case, refraction in particular. You need to provide an opaque cup or deep bowl, and a coin or small counter. Students try out the trick and try to explain how it works in terms of light rays. This worked for quite high-level students, but some groups needed extra help and guidance.