OK, I'll join in the festivities. But first, there's something that I don't understand, and if I'm right, most of the people who responded to your question here also missed it.
You are doing a science project, but you want to have a question WITHIN that project that can stump your teacher. Is how I understood this correct?
Therefore, what matters here is not just finding any arbitrary question that can stump your teacher, but rather finding a question that is relevant to the project you are doing that can stump your teacher, no?
If I'm wrong, and you just want any plain old question that can stump your teacher, then I have tons! But if it has to somehow fit in with your project, then you need to first of all describe your project in detail. Only then can we figure out something relevant to what you are doing and come up with questions that are not far out in left field.
Zz.