Science Fair Help?? Plz help?

I don't know of anything else other than what you mentioned, but iyou can do something to make the eruption higher. You can take around 7 pieces of mentos, take a paper or something, roll it up, and put the 7 mentos into the roll. Block the bottom so that the mentos don't fall yet. Unblock the roll when you've put it on top of the coke, so the mentos drop consecutively. Much better than if you only use 1 mentos