By definition, a teacher evaluates a student’s progress in any given subject as part of the process of learning and assimilating new information.
That evaluation can be helpful or lethal, depending on how it is delivered. We have all been on the receiving end of both.
As teachers, it is imperative that we tell the truth to the student, but there are ways to be truthful compassionately and ways that are unkind and uncaring. Considering the student’s well-being and self-esteem when delivering critical comments should be paramount in a teacher’s mind, but often, that is not what occurs.
There is a huge difference in being told, “The way you are singing that phrase doesn’t really work. Let’s see if we can find a better way,” rather than, “That sounded dreadful! Can’t you do better than that?” Similarly, if a teacher says, “How can you make such awful sounds? What’s wrong with you? Don’t you have any talent?” That’s very different from saying “Your throat is giving you a hard time today, Sallie. We could use some help from your body so your throat isn’t so lonely. Maybe then they would work together and everything would sound and feel better. Should we try to work towards that?”
It is possible to acknowledge that something isn’t working effectively for any number of reasons. It is possible to recognize that the process of singing isn’t going along in the best possible way and that intervention is necessary. A student might be trying her best to deliver what is being requested by the teacher, but still be unable to achieve the desired goal. That simply means the student is a student and not an accomplished professional. Students who can deliver everything a teacher requests, first time, every time, are very very rare. Even exceptionally talented and motivated students do not do that. That is often why it is so that gifted singers do not make great teachers. They did not spend much time learning to do what it is that others must be taught one step at a time.
Humility in teaching is always identifying with the student. It means that there must be a willingness in each moment for the teacher to learn something from teaching the lesson. Evaluation, done with good humor and gentleness, without condescension or snide chastisement, is both necessary and helpful. Criticism that passes pejorative judgement on another human being and her capacities is always harmful. Value judgements about the work, given calmly and without rancor, are good but value judgements pronounced with arrogance and hubris are harmful, sometimes permanently.
Value what you judge. Judge how you value it. Balance them against each other. Be aware. Be careful. Be kind.