This is a simulation of the interference of two wave pulses on a string. Choose the shapes of the pulses either by manually moving the orange and blue points up or down or by selecting from the gallery of pre-set pulse shapes on the right.[br][br]To practice pulse addition, uncheck the "Choose Pulse Sum" check box, and select the "Draw Your Own" checkbox. Move the pulses manually so that they partially or completely overlap. Now move the green points to make your prediction of the shape of the sum of the two pulses. When you think you have the correct shape, choose "Show Pulse Sum" to see if you were correct. Note that the green points can be moved left and right as well as up and down.