How does Justin react when he first sees August?

Justin is shocked when he sees Auggie, but he tries to pretend that he isn't.

i like to think i'm able to hide my surprise. i hope i do. surprise is one of those emotions that can be hard to fake, though, whether you're trying to look surprised when you're not or trying to not look surprised when you are. i shake his hand. i shake the other kid's hand. don't want to focus on his face. cool room, I say. are you via's boyfriend? he says. i think he's smiling.