Answer: i would chose a experiment that i have well researched and know how to do but nothing to common either such as the baking soda and vinegar experiment. A good one is Gummy Bear Osmosis, when i did that one came in first place. But there are several others as well.
Answer:
I would choose something that purely interest you
Explanation:
For example, I once did a science fair project on crayons and the types of temperatures it took to melt them. Not only was it easy, it also turned out extremely pretty.
