Maybe you can go try to go trough the basic technique like grip and how to do forehand and backhand. But do not talk to much, kid do not have good attention span.
Maybe you can do warm up like when kids run around the tables and hit against you at one table, or fast feet exercises by the table or maybe skipping rope.
I think it is best to do very easy exercises so the ball goes over the net alot and it will become alot of play. And throw in that they can count how many balls they do at a certain time, or first to 100 scream stop and do small games in the exercises, like maybe first to 11 in bh bh.
Then just do some easy exercises like warm up fh fh and bh bh diagonal or straigth. The letter, where one play straight and the other diagonal then change. one bh, one fh or two bh and two fh. The irish, where you do 1 bh 1 fh then 2 bh 2 fh and so on. 2 point forehand from one of the corners, or 75 % footwork. Falkenbergaren, one bh, one fh all from the bh corner then one fh in fh. The werewolf, one bh, fh in the middle, bh and fh from fh. Can also mirror this and do the opposite. Maybe one in the middle then bh or fh and back to middle. Can proably do alot of irregular exercises of those above.
Easy serve and return exercises like short short, serv short and long in the bh then loop, the same with the fh, the last two exercises but with block back.
matches like variations of the winners table.
There are some, but i think you can find alot of content on the internet and you can make up alot of exercises with your imagination.
Once again i think that aslong as the exercises is fairly simple, and throw in counting in them and games in the exercises it will go well.
Good luck!