First off, there is no such thing as “properly” when it comes to music, and his definition of “properly” is just his opinion. There are many ways of playing it, and other teachers will tell you to play Rachmaninoff differently. It’s a good idea to learn to play it the way they tell you, so that you are able to play it that way if you want, but in the end it’s all up to you to decide how you want to play it. My advice is to use the things you think are helpful, and forget the rest. A good teacher will try to help you get better. A bad teacher will tell you that you play badly, because they don’t know how to help you get better. My teacher in 9th grade told me I should stop playing because I had no talent for music. 15 years later I’m both a musician and a music teacher. She was not helpful, so I didn’t listen to her.

Criticism can be pretty tough to deal with, especially when you’re still in school because the people hitting you with it are usually your teachers. These are people that you look up to and hope to learn from. It’s pretty common that schools hire the most awesome performers to teach on their instrument, but those performers are not necessarily trained teachers and sometimes you can tell. Things like tactfulness and considering reactions before you speak aren’t always there. So it’s pretty much up to the student to either deal with it or be smashed by it.