Space awareness is the initial problem with youngsters, so I am putting some ways to teach them about meeting
the ball at the contact point.

1/. Start them of with either another player or the pro, rolling the ball towards a coloured cone. thre should be a
different colour either side of them, about a metre away. As the ball is rolled the player between the cones calls
out the colour as soon as they are aware of it, and runs to the ball stopping it with the front of their hand or the back,
whichever side it is, and rolls it back to the feeder.

2/. Give them a racquet and they do exactly the same - stopping the ball with the front or backhand.

3/. When they are getting the idea with 1 & 2, they put the racquet down and now you bounce the ball to them (not
too far away to start) the progression is now:

A/. stop the ball with the hand

B/. catch the ball on the forehand and stop the ball on the backhand, but they should make a fist and try to stop the
ball with the  front of the thumb.

C/. Pick up the racquet and choke up to the throat, repeat the forehand and backhand stopping the ball with the
racquet.

D/. Move the hand down the racquet in modules until the player is holding at the butt.

E/. Don't worry too much about grip at this stage and gradually move further away from the junior.

Voila, you have a system to work with.