Fool your eyes -- and learn what makes movies move -- using this super-simple animation technique.
Fold a sheet of paper in half, then unfold it and use a marker to draw a simple figure on the lower half.
Refold the paper and trace your drawing, but make a couple of changes: bend an arm or leg, draw a different mouth, or move an object.
Make a cut on each side of the top drawing to create a center tab, then roll the tab around the marker to curl it.
To animate your drawing: Repeatedly and rapidly slide the marker up and down the page so that the tab curls and uncurls, revealing first one drawing and then the other.
What's going on: It takes your brain more time to interpret each drawing than it does for you to flip between them. As a result, the quick and repetitive switches cause your brain to blend the pictures into a single moving image the same phenomenon that makes movies possible.