1) Start from a standing position with your feet at shoulder width and your hands by your side.
2) Inhale and slightly lower yourself as you would with a squat. As you are lowering yourself, swing your arms behind your body - this will help generate the force.
3) Exhale, drive your arms up and push off the floor through your heels. When you jump up, instead of keeping your legs extended, tuck them in towards your chest.
4) When you land, bend your knees to absorb the impact.