1) If you are really using the warm up to it’s fullest potential (wink, wink) you should be almost sweating by the end of your plies! I know it sounds like you would have to do killer plies but it’s true. During a plie exercise practically every muscle in your body has to work, so if you put energy and focus into your plies it will warm up your muscles fast and furiously.
2) That being said… sometimes dance studios are really cold, especially in winter, so it’s best to choose some warm up gear that teachers will accept. The main factor to look for is does it allow the teacher to clearly see what’s going on? The scary thing is that if a teacher cannot see what your muscles are doing you might be doing something that can cause serious harm to your body. So, choose gear that emulates your dance uniform only in heavier or knitted materials. Some classic options are below and often come in fun colours… however; most of your teachers will prefer a colour that matches your uniform.