Body Weight Squat
Body weight squats are an excellent exercise to learn proper squatting technique. Performed with the correct tempo (speed of reps) the body weight squat can be very challenging especially when combined with other exercises within a giant set.
Remember to initiate the movement by pushing the glutes back which will support the knees traveling within a favorable path. Aim for a parallel depth on the bottom of the squat position unless an injury conflict exists.