you just need to practice
Best way to train to not "hang" material
you just need to practice
Practise what? Are there any particular drills / training exercises you should ask them to do, or just continue playing lots of games?
Maybe ask them to stop in a position and point to all the squares that are covered. Or ask them all the squares a specific piece can move to without being captured?
Not for me, but other beginner players I have observed, mainly by watching their streams on Twitch.
These are weak players and obviously when they stream, we try to help them improve their game, but they are prone to simply hang material, i.e. move a piece to a square where it is attacked. They ought to know better, and they'll usually see it later, and maybe they will even avoid it most of the time, but they still tend to do it.
Once feels that if you can train them to stop simply hanging pieces their game will improve, but how to do so? What kind of puzzles / drills should they do?
Similarly they do not always notice when there is free material there to capture, i.e. when the opponent has simply hung something.
These streamers are usually playing 15+10 so a reasonably slow time control (which I believe is necessary for them to have time to think).