This applet displays the graph of a sum of the form "sum for k=N to M of f(x,k)", where the lower and upper limits N and M are specifed by sliders at the bottom of the applet. One of the terms in the series is displayed in a separate graph. The term that is displayed is specified by a third slider. The sample function is the series for sin(x). It would be nice if the upper panel also displayed the function being approximated by the series. I will add this later.