Hi April,
seems I guessed correctly, there. It appears we would be at the risk of ruining your son's creativity by (if I'm unkind about it) spoon-feeding him with suggestions.
I would not be surprised to hear it is part of the learning process to gain an understanding of just how difficult it is to create an idea from nothing or, rather, do it in an environment already rich in technological 'stuff' where the first 50 or 60 things you dream up all turn out to have been done before by someone else. It's analagous to being a musician and trying to create a new song whilst constantly checking to see that you're not plagiarising something from the past.
A week of him 'sleeping on it' might do the trick. If that doesn't work out, ask him if the teacher has got around to explain the concept of 'brainstorming' yet. It may be the idea of the course material is that they arrive at this technique for themselves. Learning to bounce ideas off other people is a big part of working as a team. Choosing which idea to run with is the easy part.
By the way, I fully admit to lacking in inspiration myself. I have zero ideas of what to do with double-acting cylinders.
Best of luck. Let us know how things turn out.