Make your own window stickers- these stickers are so fun for kids and can be stuck and re-stuck! Glue Food coloring or watercolors Holiday scents- we used peppermint extract, cinnamon, vanilla extract, and homemade gingerbread spice -
Balloon Rockets - I've done this in several science camps I've conducted. Kids have fun with it. But, when the balloon deflates it may fall off the straw because it's surface area changes - another good thing to show and explain to kids.