Build a Better Solar Oven: Investigate Optics!
Last minute brainwave – give kids a little conceptual background for how solar ovens work and teach some optics. Literally 5 minutes before class, switched it all around. Don’t recommend this, but done!
We are so lucky, we have cool light boxes that can project light rays with cute little clear plastic lenses and little mirrors to bend the rays around. I put them on top of giant white board so students could draw the rays in easily.
The intro was all about how can mirrors and lenses be used to concentrate light energy. The more concentrated the light energy, the more energy that can be transformed into heat to cook food in a solar oven. Gave a quick demo for how to use the light boxes, lenses and mirrors safely and without melting or burning anything. Then they got straight to investigating ‘Which mirrors and lenses can concentrate light rays? What is the ‘law of reflection’ on a flat mirror? and ‘Can you make a rainbow?’ So, so much better than ‘follow the recipe’ worksheets. Very high energy, lots of experimentation and I could circulate, question, check everyone knew the directions and coach. Kids had to write notes and make sketches in their notebooks and I look for completion and thinking, not necessarily the right answer.
Wrapped up with ‘Hold up the things that concentrate light and bend it to a focal point’. Then made the link to how they might consider using convex lenses and concave mirrors in their solar ovens. They showed how to make a rainbow and we talked briefly about white light being made up of all different colors or wavelengths of light, and that shorter visible light can be converted into longer wave lengths off the red end of the rainbow – infra red or radiant heat. Also handy review for use in their solar ovens.
Another exercise in letting go a little for increased student engagement. Where are you trying this in your classroom?