They do not get much privacy. I worked as an electrician for the ballet company and often a dancer has to do a quick costume change. They may try to set up a sheet or some sort of a make shift dressing room but for the most part they were expected to do that in public. I got called out once because I was allegedly looking in that general direction when they were changing. I was not looking at anything. I was there to move a grand piano on and then off stage and I was just waiting for my cue. I was informed that they were naked during their costume change but I did not see any naked dancers anywhere. There was not even any lights on back stage. It was all in the dark. Teen girls are going to be even more sensitive about having to do their costume changes in less then private conditions. They dance off stage and have to do a quick change to dance back on and they really do not have time to find a dressing room somewhere.