This one comes from a great coach named Vern Gambetta. The focus should be one rep per second. The fast work results in extreme soreness.
Bodyweight squats x 20 reps
Lunges x 10 reps each leg ( should be as long as the person is tall )
Step ups x 10 each leg ( should be alternating on a box about 14 inches high )
Squat jumps x 10
You could repeat this after some rest, or just use it at the beginning of a workout.