Science Experiments For High Schoolers

Question: What are some good ideas for impressive science projects?
I started home schooling last year and I’m hoping to apply to college full time next fall. (I’m just thinking ahead :] )
and since home schoolers don’t have a portfolio and grades from high school, we have to show lots of sample work in different “subjects”. The one I’m lacking in is science, mainly bio/chemistry. I’m hoping to apply for an Equine Science major and I need some ideas for “impressive” projects where I can experiment, read and/or make a model/poster or something like that. It has to be something that they would make you do junior/senior year of highschool. Any ideas would be really appreciated
Answer: See the movie: The Manhattan Project
Fun Science Projects for Children : Ingredients for Flubber