Some science fair projects can be how a volcanoe erupts and explain the heat and process of lava, and how a volcanoe forms. You can do the structure of atoms or the structure of a nuclear atomic bomb, and nuclear structure. You could do classification of different rocks and fossils. You could do a study on bacteria out of pond water or even pool water, and name the bacteria, and chemcials on how to treat it, or even explain how the bacteria forms.