View full lesson: http://ed.ted.com/lessons/got-seeds-just-add-bleach-acid-and-sandpaper-mary-koga
For a seed to start growing, its embryo must emerge from its hard coat. In nature the embryo is aided by frost and animal digestion -- but humans can help too. Nicking, filing, and soaking the seed in hot water or acid are all forms of scarification, or ways to speed up germination by breaking down the shell. Mary Koga offers some tips to spur your sprouts (and don't forget the bleach!).
Lesson by Mary Koga, animation by Provincia Studio.