Before you start. One idea helps: light is a wave, and each colour is a different length of wave, red the longest and violet the shortest. Why the Sky Is Blue uses the same idea for the sky; if you have read it, you have what you need. If not, the sentence above is enough. A soap bubble or a CD will make this lesson easier to see.
Continue reading with a plan
The first three lessons of every track are free. This lesson is included with a plan, which unlocks every lesson, board, video, lab and paper for one price.