Boy or girl!?

So school just started and there’s this person in my class.Im bisexual but have never really had an official boyfriend of girlfriend (I’m a sophomore) this is really weird to say but the person in my class seems kinda cute as a girl but the problem is I can’t tell if they are a boy or a girl. And idk if I should ask them cause that’s kinda awkward and can be rude if they are trans or something. And I wouldn’t consider them attractive if they were a boy but I would as a butch girl.....what do I do!