This is a simple, fun way to demonstrate the divide-by-2 potential of the D Flip-Flop. Increase, or decrease, the clock signal, and turn on the scope function, with the clock input and Q output of each flip-flop running. The LEDS just add some fun stuff to the circuit. How many Flip-Flops you add depends on how far you want to go, and how much screen resolution you have.