Freehand Jump Squat

How to do it

Cross your arms over your chest.
With your head up and your back straight, position your feet at shoulder width.
Keeping your back straight and chest up, squat down as you inhale until your upper thighs are parallel, or lower, to the floor.
Now pressing mainly with the ball of your feet, jump straight up in the air as high as possible, using the thighs like springs. Exhale during this portion of the movement.
When you touch the floor again, immediately squat down and jump again.
Repeat for the recommended amount of repetitions.

What muscles does the Freehand Jump Squat work?: Mainly the quads, with help from the calves, glutes, hamstrings.
What equipment do I need?: Nothing but your bodyweight.
Is it good for beginners?: It is rated intermediate level.
How do I track progress on it?: Log each set and beat the weight or reps from last time. Liftrung shows your last set beside the next one and estimates your one-rep max from your sets.

Exercise descriptions: free-exercise-db, public domain.