Ava freezes up in response to being noticed, because it goes against her idea of what it means to 'blend in' that she's trying very hard to prove herself capable of. Okay, she practiced this in the mirror several times. Don't mess up. "Hi," she echoes in her dainty voice, the barest hint of her accent punctuating the single word. "I'm Ava." See, not so hard.

Except he asked a question, so she has to keep going. Off script. But that's fine, she's supposed to be able to improvise, isn't that what her trainer had told her? "Sorry, I'm used to looking at the back of everyone's heads, so I didn't recognize you." Oh, that sounds like a weird thing to say, even if it's true.

She continues fumbling with the lock, not even paying attention to what numbers she's turning to now. "You're... uh. New, right?" Because maybe she's not so great with interacting with anyone, but she has been paying careful attention to all the other students, trying to learn from them, even if she hasn't been able to fully bring herself to participate much yet.