How to avoid time trouble?

Most beginners don't have this problem. If your child is prone to time trouble, you should help your child analyze his/her time usage. Write down time used for each move. Check average time needed for one move. If it's too long, s/he should try to speed up on trivial moves. Sometimes it's really unnecessary to think too long when a move is forced. Make the move first, then try to use your opponent's time to think.

If the problem is on a few moves, look at the game to see whether they require that much time to think. Find a way to break the circuit. Get into the habit of checking the clock from time to time. Pick a time, such as 10 minutes at most for a move, stop there no matter what.

Analyze your kid's behavior during his/her games. Is s/he walking around too much? If yes, then suggest to sit down longer. There is absolutely no need to look at other people's games. 

Try to use his/her opponent's time to think. Yes, the move is not there yet, but s/he can think against all possibilities. That's how s/he does his/her calculation.

Solve a lot of tactics problems. Build a correct thinking approach. Use a timer so s/he can learn to make judgement call when time is running out. 

Play more blitz games, so s/he can move faster.