It really matters where you work. If you are in chinuch (men and women) they should be dressed respectfully and dignified. No, denim and jeans are not respectful clothes. Have you ever seen a rebbi in a t-shirt and cotton pants? I sure hope not. No one said they have to dress to kill but there is a certain amount of respect and dignity that comes along with dressing well that is very important in the world of chinuch.
Dvorak, OMG! i feel bad for your teacher!