Make sure that your child takes notes, books a practice court and drop feeds at least once or twice and works on the shots practiced in the lesson by themselves.
Make sure they book a court with the ball machine, or hit on the wall.
Make sure they spend some time on youtube looking for a role model that they can use to watch.
Make sure they practice technique correctly in front of the mirror.
I see a lot of people thinking that working on a shot for ten or fifteen minutes in a lesson will do the trick. This is where the correction is learned, perfecting it takes practice.
Doing the "practice" part of learning a shot with your coach is very expensive.