Here's a great foot warmup to help students warm up the feet and help with their sur le coups de pied.
Position: Facing barre, or back to the barre, in 1st.
1: Ball of the foot, sliding the foot in so the heel is to the front of the ankle
2: point and wrap the toes around to sur le coups de pied
3: "flick" the toes back to the ball by placing the tips of the toes on the ground and rubbing them out back to the ball
4: slide the ball of the foot away as you place the heel down.
5-8: repeat with the other foot
1-2: 2 pop-ups in 1st
3: pop up and close in 5th front
4: pop-up and close in 5th back
5: pop-up and close in 1st, demi plié
7: demi plié
8: stretch the legs straight.
repeat starting with the left foot.