Squatting down to a 90 degree angle explode up jumping off ground as fast and as high as possible. As soon as feet touch ground repeat as quickly as possible.
Similarly to skipping leaping from one leg at a time and jumping forward and upward alternating from one leg to another
Jumping onto a 18-36 inch box up and down with both legs
Box jumping one leg
With one leg on box explode up onto box and step down and repeat