Let's start your research.

You are looking for a nice experiment, Check the long required list of criteria for your experiment :

Experiment has not been chosen by someone else already ? (see on the onenote page the list of experiments)
Not dangerous
Material needed seems to be fine (check with the teacher if you don't know)
Interpretation is accessible to you and your public
Not too long to show ?
Interesting to see ?
Allow some interactions

If your experiment fits, you have to propose it in the discussion area to be sure to be the first group