Ken over at Music is Not for Insects has a great post about teaching students to be critical of their own playing.  I am quoting directly here:

“I really encourage my instrumental students to be honest and objective about their playing by constantly asking questions about what they are hearing and to immediately assess their performance with the help of others or by listening to recordings of their playing. I often make a big deal and applaud students when they can identify a mistake they have made after playing something. I say “if you can hear your mistakes, you can fix them.” This encourages them to take responsibility for their playing and growth as a musician. Assessment and especially self-assessment in instrumental music is a process of learning how to evaluate, reflect and change one’s practice.”

I thought this was great advice.  I always find myself telling my students where they made mistakes.  After reading Ken’s article, I realized that I’m not helping them at all if I never let them discover their mistakes on their own.  So now I am turning my responses to their playing into questions rather than statements.  I ask them to grade their song.  I ask them what parts were difficult for them.  I ask them if they think they honestly played well.  Asking these questions allows me to discuss the things I want to discuss without forcing it into my student’s brains since they are discovering those very things as they ask themselves honest questions.