Kaleidoscope
Our kaleidoscope is assembled from a small Petri dish, a set of acrylic plastic mirrors and some stained glass and plastic fragments and beads.
While our approach is not the cheapest way to fabricate a kaleidoscope, it is amenable to fabrication in large quantities and can be constructed by students with basic hot glue gun skills, and the optical quality is good.

See the kaleidoscope page and the mp4 video (4.3 MB .mp4 file) which will stream if you have the QuickTime plug-in for your web browser available here.

Barometer
Here is our version of the time-honored aneroid barometer made from a balloon and a cup. When used properly so that the effects of temperature change are minimized, it works well and is a great student project for advanced elementary school and middle school. Of course, it also makes a great altimeter.

See the barometer page .

Alka-Seltzer Rockets
Here is the standard Alka-Seltzer rocket, most of which we borrowed from other authors on the web.  But it's still very cool and it's hard to beat the price of assembly.

See the seltzer rocket page .