Solar Pizza Box Cooker
A great project for exploring thermodynamics (conduction, convection, radiation), low cost, and fun way to capture the sun.
The basic principles of solar oven design can be applied to Passive Solar Homes as well.
Instructions pdf (from Your Solar Home Student Guidebook)
Oven thermometers available for sale in Solar Schoolhouse Store
Video Tutorial (12 minutes) - tips and tricks for building a successful pizza box solar oven.