Students need to be taught how to fix issues with their playing right from the beginning. One way I do this is to pass out these pretend doctor's diagostic forms. I then play a short music example for my students while purposely doing something wrong. Students then write down on the form the things I do wrong and what I need to do to fix my playing.
For example - playing too close to the bridge, playing with a crooked bow with bad tone, holding the bow incorrectly, playing with a collapsed wrist and bad intonation...
It is very telling to see what the students write on their papers. I can instantly see if they understand the concepts I am teaching in class about technique.
Visit my store and I will email you this diagnostic worksheet free with any purchase!