This project is for older students or for younger students with adult supervision. A reflective hot dog cooker can be built from a cardboard box, tin foil, and posterboard.
Sunlight hits the reflective surface and focuses on the hot dog held in the center.
Students can work in pairs or individually if there are enough materials. One template could be used for all the cookers. Trace the curve on the open end of the box so that it is centered and straight. Cut out the curve with a utility knife. Stress the importance of being exact.