Drag the points around to see the curve changes! This project uses a concept called the Bézier curve: http://en.wikipedia.org/wiki/B%C3%A9zier_curve The weight slider will adjust how much the curve 'bends'
Whenever you draw curve in scratch, what your actually drawing is a Bézier curve! If you've ever used Inkscape before and drawn a curve, your drawing a Bézier curve! You use them alot more than you think!