A good way to come up with a scientific question for an experiment is to?
This question has to be testable and has to come from observation. It can't be an opinion and has to be able to be answered through experimentation, although it shouldn't take a bunch of different kinds of experiments to solve. It's also good to make a scientific question that you already have a bit of information about. Being specific is also key, then your experiment doesn't have to be complicated and observations don't have to be extensive.
Hope this helped! Let me know what else I can do!