A fun explanation of an easy thing to do at home
Much more fun and easier than it sounds; never fails to impress
Very relevant, and fairly easy to do; uses the Internet, and direct observation, and statistics (4th grade)
Good for both early grades and grades 4-5, a variation on the old "electromagnet nail" and uses a Slinky to boot
Great resource for parts and kits
Some ideas here for 3rd graders who have studied sound
