Split water into hydrogen and oxegyen. Perhaps the HS moves like wind - really there even though he can't be physically seen
use a balloon to "air" power a fountain. sites doesn't actually tell you how to do this experiment but this is what you could try. (See Comments)
Experience real science with a hands-on project you can do at home! Here is a project you can help your kids create. It is educational and fun at the same time.
So many great science experiments and activities!
turning the arrow experiment (refraction of light lesson)
This is a great chart to use with your light unit!
Electricity Anchor Chart Miller's Science Space: New Anchor Charts
Make a Photon Flower That Lights Up When You Water It with Lemon from Instructables
This is very elementary, but... Middle schoolers would still love it! It involves cutting & pasting & coloring!