I am a piano teacher and have a couple of kids who have very low-esteem in the US. I was raised in another country where the parents and elementary school teachers usually discipline their children, not necessary in a harsh way. As a comparison, in the US, parents usually give their children too much and not discipline their children much.
Kids who do not put their effort in practices yet expect to be superstars still EXPECT me as a teacher to say nice things about them and pamper their behaviors. They do not listen to the instructions and just have an attitude. I have to be clear here though that I am always rated to be the nicest teacher at the school. I have never used any harsh or discourageous words to kids, because I am so afraid that I would hurt them or discourage them in any way. Even if they play really bad, I still cannot open my mouth to say anything negative. I am so careful not to use any words which would sound like "judging."
Having said that, I feel that the kids do NOT care however they do, for there is no impact on them that they need to improve any further......
I can be straighter with the kids who have normal self esteem, even though I am not out of the range of "being nice." They can practice on the areas that they need to work on more, because they WANT to get better. It's so different about these low self esteem kids. They cannot take anything they need to improve, yet they know that they are not doing that well. It's up to a point where I cannot point out any wrong note. By the way, i even don't call them "wrong notes" when I point them out, but I just show them how to count from a note to another in order to find the proper note. However, they already get so DEFENDED about it.....
I don't know what to do then, if a teacher can only give nice words without straight things up. If I keep doing this way, they are wasting their time and energy struggling. However, if I straight them up, they cannot take it. I have seen many American kids so vulnerable and fragile emotionally, because they are never used to disciplines or judgments. Little matters can hit them hard. It is like a person who grows up in a germs free environment, he is not going to build up enough immune system to fight for sickness.