Ineed science fair ideas for 4th grade, but i need something that won't need a oven, sunlight, etc. also, i need something that isn't common (example: volcano) but still simple!

Something simple?
Hmm, how about a diagram of a fod chain? Its simple, if you dont have a printer to print the images of a food chain, or animals, then just try to draw it the best you can...
Make it into a poster, write some information about the animals, who eats who, are they a carnivor, herbivor, you know... Stuff like that :)
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Hope this helped! :)

Because the dept in the ocean