Play Recipe- How to make your own glowing bounce balls This looks like a fun activity. I'd recommend reading the entire entry before doing this with your class. The author did it at home with her children only.
MAGNETIC SILLY PUTTY http://frugalfun4boys.com/2014/03/06/make-magnetic-slime/ Your kids will be in awe as you can move this slime with magnets. If your kids have a science project to do, this will wow!