Miranax,
What you asking for is gold dust. As soon as someone posts a good experiment everyone will copy it and claim it as their own! Here are some ‘throw aways’ for you to try:
A kid’s experiment published on the net called craters involves dropping balls of different sizes into a variety of materials, such as flour, sugar or pearl barley, etc. The goal is to produce the largest craters!
I don’t know if this will give an interaction, but you can try it yourself and find out!
Other ideas I’ve considered include mutual inductance, Chladni’s figures, and Lego racing cars. (For the latter I glue several pieces together and hide blobs of solder in one combintion and ask teams to ‘fault find’ why one car goes further when rolled down a ramp than the other.
Sorry I can’t be more helpful … good luck!
Andy
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