The grade is up to how diligent you are. Below are some sites that have lots of science fair projects.
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Science projects for teens include: hometrainingtools.com/a/science-projects 101science.com/science_experiments.htm education.com/science-fair/physical-science/
what are some catchy titles for sience fair projects about milk
Some science fair projects that can be done using Coke are to see if the soda will dissolve a nail, can it clean a penny, or what effect the soda has on the teeth. Another project is to make a Mentos geyser using the Coke.
Egg flotation, exploding volcancoes.
Power hour
make pancakes. it shows convection conduction and radiation
what are some candy science fair projects?
Somehow compare the two, acid rain and regular rain, taste, how they feel, the look, and how it can affect nature. Then give off some facts about it.
test plants with different light sources
Well I'm guessing I'm to late, but baking soda volcanoes are great or you could go to youtube and look up home made science fair projects.