Science Buddies: "Ask an Expert"

I am doing a science fair project with my friend. We are stuck for ideas. We need to do bleep to do with the environment. If anyone could help us please do. We are in 9th grade and we really need ideas. We need bleep that is going to take a while and be interesting. We have 1 month to do this and we need our idea quickly. PLEASE HELP US! THANK YOU SO MUCH!

You can do "Which rock is best for your porch?" Pretty much all you have to figure out rain effects different types of rocks. You can see how much sediment is weathered when you pour water (or acid rain) on the rocks for a certain amount of time.Use materials such as brick, marble, granite, woods, etc. This project demonstrates the interaction between the environment and humans, so it fits your guidelines.