Some schools, such as the one I went to during high school, had a really strict dress code. Students couldn't express themselves for dreading of getting sent home or even suspended from school. Schools should let their students have freedom of their own expressions. Either by the way they dress or something as simple as a drawing in art class.
Having schools take freedom of expression away from their students isn't going to improve anything. Not only can't they display themselves on the outside, but many times they can't even speak their own minds. You might as well take their whole identity away from them completely. It doesn't allow them to develop themselves if they always have schools and teachers telling them what they can and can not say, draw, wear and so on. When students get to their teenage years in school they all go through a phase to see where they belong. Many of them will want to express themselves by maybe by joining choir or a sport. If the school tells them they can't sing a certain song or play a certain sport they will feel like they are missing out on something. As in a classroom, many teachers won't let their students write about a certain topic or even have it discussed. If they had that option of learning and listening to other points of views, of whatever issue they might be discussing, they will gain knowledge of others. They will never get to show or know something new if they are always restricted about expressing themselves to others. Many of them also express themselves .
through dress. The way a student dresses is their image, if that is taken away .
from them they will feel dull and sort of imprisoned because they won't be able to show others how they really feel inside if they can't express it on the outside. Many of them might become rebellious which can then cause problems. .
Of course, having some rules of how students should dress, act, etc.