The students at this summer school have applied to attend. Most of them will have come from comprehensives, I believe. I'm expecting that they'll be pretty motivated. I'm going to plan a couple of short additional activities to measure noise and feedback in case I get an exceptionally quick group, but otherwise I'll stick to the central one. You're right, it is difficult to be flexible, especially when faced with a group of twenty students whose ability levels and interest vary widely. Fortunately, this project will have a maximum of five students working on it.

Thanks for your input!