Rocket, try not to put any credence into practice scores. If you are practicing something new, the score means nothing. He doesn't need the added pressure to score high while trying something new.
Like, practicing spares. When you try for a ten pin only, it doesn't matter what pins are left up. So, on the first ball, just shoot for the 10 pin. You should still have the pocket left up to shoot for a strike ball on the second try. In this manner, he gets practice, and sees the score is meaningless.
Move him either direction on the lane with his feet, and have him aim at a particular arrow target. Let him assess if he hit it or not. Again, score is meaningless but accuracy improves. And, he learns how to play angles.
Some bowl just practicing. Then bowl the final game for score, using what he has learned.
Some of us here even shoot ten pins, then 7 pins on the second ball. Objective is to get the lowest score, without a gutter. A perfect low score would be 20.
LM - Black Diamond 15#
Lord Field - Exodus Pearl 15#
Legends - L/M New Terminator 15#
Legends - L/M Xtreme Damage 15# Strong pearl