Telling students to hit down on the ball isn’t the answer. If they always miss the ground it’s either a concept or fear thing. Their concept is wrong because they think they can lift the ball off the ground. I explain why it’s possible but leads to poor contact, then have them hit balls off of a low tee making sure that they don’t hit another ball until they get the tee out of the ground. I explain that the only way to get it out of the ground is to relax and let the club head be drug through the ball / tee. Tension is brought on by fear and poor understanding of how tight the club should be held.