Last year, my son's friend was able to obtain a water-testing kit from the city water department and did water tests on different areas around where we live (all are on different water systems). I only know that in our area, it is a competition and he won the county-wide contest; I never actually saw his project.

There are a lot of great ideas online... and doing the experiment correctly (using 'scientific method') is what our local judges look for more than anything else.

I'd suggest doing something that is interesting to your son... My son is interested in Music and we did one this year (turned in this week) using harmonics and testing sounds that he really got into.

Good luck. Coming up with the idea is definitely the hardest part and we've had to do it for too many years to count and I can't stand it. We don't go for *the win*... we do it because it is 'required'. Sad but true. LOL.