Wired magazine have an answer what to do with all of those leftover Valentine’s Day chocolates (if you have any). A microwave and some chocolate can be used to measure the speed of light. It is a simple yet surprisingly accurate method that can be used to introduce the scientific method to children. The details can be found at Leftover Valentine’s Chocolate? Use It to Measure the Speed of Light article. You get the 2450MHz microwave wavelength from the melted chocolate hot spots.