5 x 6 reps, 2 min break in between. Use a light weight and make the jump as explosive as possible.
Start in a standard lunge position. Your chest should be upright and in line with your toes. Your back leg should be almost fully extended with your knee just off of the ground.
Start with a small counter movement and explosively jump up and switch your legs in the air.
Land with soft knees by catching yourself before your back knee hits the ground.