<p>Usually, how well are you supposed to know a girl to ask her to prom and not have her be a little surprised?</p>
<p>have you ever talked to her before? does she know your name?</p>
<p>If both answers are “yes” then go ahead.</p>
<p>^ haha</p>
<p>I would say you should be friends with her, as in talk to her on a fairly regular basis. Best case scenario would be you’ve hung out outside of school (even in a group) just so it’s not awkward to see her somewhere other than school. But to be honest, as long as you know her she’ll probably be relieved to have a date. Go for it</p>