Good to see you're enjoying teaching. This is the most important stuff ! If you're enjoying teaching they'll enjoy learning.
Here are some good coach memories ? hth
1. They're kids, they need images, mnemonics, easy stuff they can rely on when everything goes wrong. My 1st tennis teacher, an old spaniard stopped drills everytime I was not moving to the ball the right way. He stamped on the ground yelling "pierna pierna pierna !".
Everytime I find myself with a lazy footwork today I still remember him
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I'm sure you'll find funny stuff like that to help them remember important things. If they laugh when you use such mnemonics : u can be sure they're having fun & u can also be sure they'll remember it.
2. You should communicate ur tennis passion. For that matter, u can use pro players pictures to help u. Kids need idols, players they can refer to. Use pictures, posters. I remember learning my 2HBH ending thx to a poster of Kafelnikov with his left elbow in front of his eyes.
3. You should be their coach & also their friends. You should be strict, obviously, and teach them to be rigorous. But keep in mind they'll learn faster if u're their friends and they enjoy playing with u.
Example : I was a very anxious kid when I was adolescent. And sometimes tennis lessons were a disaster : mishitting, getting anxious, getting angry, ...
1 of my tennis teacher yelled at me that I should be calm (paradox...). Desastrous effect... Another 1 though, recognized when I was "tilting" and stopped the drill right away. Fetched soft balls from his bag and gave me easy balls on my FH, telling me : "Ok now u're angry, just hit as hard as you can, idc where the ball goes, just hit as hard/dumb as a donkey". That was exactly what I needed, he acted as a friend, not as a teacher.
4. Since they're young, u'll be their model until they're able to "build" their game on their own.
So be very very careful about how you play, obviously... Example : I was a huge fan of the heavy crossed slice FH my teacher was hitting when he was really outflanked by his opponents, you know the "last chance defensive slice". And I was sometimes being lazy on my footwork, just so that I'm away from the ball and can try to hit that FH.
Be also careful about your language, body language and mindset. Kids are sponges at this age. They'll mimic whatever they see. For instance, don't be harsh on yourself. Don't use words like "that sucked, I sucked, that was bad, ...". Always be positive.
It'll help them alot to build a positive mindset. Correct bad attitudes as soon as u're seeing them. It can be as obvious as dropping the racquet but also being passive/agressive, or even just sad.
Be aware of that, and learn how to react with the kids properly:encouraging them on their next good hit, switching drill, ...
hth, hope u'll be a very good coach !