2" flywheel in a well-made metal frame. The trick is the same as it has been for 100 years. Wind the string through the spindle, pull it firmly to set the flywheel spinning, and perform effortless balancing magic on pencil tips, string tightropes, and the like. We tend to forget that bicycles and aircraft navigation both rely heavily on gyroscopic principles. It's never too early to tell the kids. Besides, it's fun.

Rattlebacks are plastic semi-elliptical shapes, 3-7/8" long, that illustrate Newton's laws of motion, while mystifying kids. Set them down (the rattlebacks, not the kids) and their offset center of gravity makes them spin. Spin them in one direction and they stop and reverse themselves. You get a package of (10) in blue, along with a lesson plan and suggested activities.

We just learned that. You’d think we’d have known. Now we do. They’re sort of like round dreidels, with a hollowed-out middle around the stem, which causes them to turn themselves upside down while they’re spinning. Great lesson in center-of-mass instruction for physics teachers. Includes an explanatory booklet with activities and discussion topics. You’ll get (3) wooden tops at 7/8”, 1-1/4” and 1-1/2” dia.

Spin this spindle and watch it turn in perpetuity!!  Well, for a long time anyway.  Inside the 5-1/2" long colored plastic spindle are magnets which are repelled by magnets in the 5" x 3" black plastic base.  The variously colored spindle floats in the air above the base thus virtually free of normal friction. Nifty desk toy named "Revolution".

Please note #91664 with flashing red lights was incorrectly advertised, that item is not available. 

In the mood for a little light levitation? Try this magnet-based kit from KidzLabs® and make a pencil float in mid-air or tell your fortune, all through the captivating power of magnets. You can even build a mag-lev robot, and who doesn't want one of those? The (7) projects are based on the (7) plastic-coated, 1-5/16" dia bored disc magnets and assorted other parts. Projects include anti-gravity sculpture, floating spinner, magnetic compass, spring and weight scale, propelling machine and a mag-lev transporter.

A tiny touch of whimsy from your local scientific and surplus monger. You get a trio of 1-3/4" dia x approx 2-5/8" tall plastic tops in assorted colors, with the American Science & Surplus logo on the disc. The tops of the tops have a vaguely Constantinopolitan shape, and are a different color from the bottom. Just one more dazzling detail from Jarvis.