This applet shows the area under a curve approximated with rectangles, Riemann sums. The upper and lower sums are shown as well as left, right and midpoint sums. The number of rectangles can be changed with a slider or animated with the play button. A key concept is that the upper and lower sums converge as the number of rectangles is increased. Questions also include the relation of the other sums as the number of rectangles increases.
