The science fair was in 6th grade and I remember Mrs. Tucker, who I think focused on English in college, NOT science, despite the fact that she was my science teacher then. I say this because it was her that made me realize that teachers do not know everything and only the good teachers will admit that. When we were learning about gravity and how it works (it's two masses being attracted to each other...everything has gravity, only since earth is so big, it's gravitational pull overrides all else), I asked her what would happen if I were go to the very absolute center of the Earth...would I float there b/c all of the gravitational forces that encircle me perfectly cancel each other out, or would I explode b/c the gravitational forces are pulling at me in all directions? Her answer: It doesn't matter, you can't go to the center of the Earth. I kept on saying "Yeah, but what if?" and she was like "NO, IT DOESN"T MATTER, THAT"S AN IMPOSSIBLE!" So I dropped it.
But I asked every science teacher I had after that the same question. The ones who answered it were Mr. Wessling and Dave. I don't think I asked Calvin...I should have. I don't remember what the answer is, I just wanted to get one. oh, sidenote: the ones who answered it were geologists, mostly because we only deal with "what ifs".
Back to the science fair, as an example of what someone could invent, Mrs. Tucker said she would like someone to invent a way to dispose of cooking grease easily. Christine Slate said that she could, and Mrs. Tucker was again all "NO YOU CAN"T IT"S IMPOSSIBLE" but Christine did anyways. She put a screen over a coffee can and then you pour your grease into it and then through away the can. It's not really an invention...probably on the same level as a Snuggie, but it worked.
Many municipalities that are running their own biodiesel plants to fuel their fleets and save taxpayer's money run cooking grease recycling centers, where people can drop off their collected grease and it's made into biodiesel. Now if that isn't an easy way to dispose of cooking grease, then I don't know what is.