This website has hundreds of great hands-on science ideas in biology, chemistry, physics, earth sci, and more! Many activities are simple enough to do with an elementary school class. Pictured here: An egg floats in salt water
It would be seasonally appropriate to do this experiment during the fall to show teach students why leaves change color. I'm sure many kids wonder why this phenomenon happens, so this would be a really enlightening experiment!
This craft stick harmonica is fun to play, and you can adjust the pitch by moving the straws! It’s a neat project, and a good one to make with a group because the materials are very inexpensive. You can fit in a little science learning too – see the bot