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.
I love this pompom rug so much! poof round rugs made of pompoms:-) What a cute hackable way to use up little end bits of yarn! I would just stitch them down to cross-stitch fabric and then add an underlay.