Plate choctonics

I'm helping out with a schools geology event next month, but don't know what I'm doing.  All I've heard about it so far is that it is likely to involve chocolate.  Given the time of year, and my love of Dairy Milk, I've no problem with this at all.  However, I do hope it uses scaled-up Creme Eggs to explain plate tectonics.

The egg-sternal and internal structure of the Earth