Applet allows for students to drag 5 key points of one period of a sinusoidal wave so that the graph displayed matches the simple trigonometric function (of the form "y = a cos(x) + d"displayed in the upper right hand corner of the screen. Once a student correctly graphs the displayed function, the applet will provide him/her with immediate feedback. A new equation can then be displayed at the click of a button. Students can repeat this exercise as many times as they need to master this concept.