Start on all fours with your hands underneath your shoulders and knees under your hips. Keeping your knee bent 90 degrees, lift your left leg until it's parallel to the floor.
Keep your left thigh still as you straighten your left knee, kicking your leg out to the side. Don't let your leg lower as you kick it.
Bend your left knee back to 90 degrees, then lower your leg. This completes one repetition.