Panel 1: Crimeny, it's just like on Full House: There's never anyone in the hallway except the main characters. Also, why does he just say "room"? Why not "homeroom", or, as in my high school, "student group"? And for that matter, you'd think they'd have done some kind of orientation, like they did at my high school, where they herded all the freshmen into the auditorium to sort them alphabetically. None of this just waltzing in and saying, "Oh, I'm in C104." (Although to be fair, April and pals have been in this building before, whereas for me and my classmates, it was totally uncharted territory.)
Panel 2: Very stilted dialogue.
Panel 3: Another mostly-empty classroom. I can't believe the doorway wouldn't be jammed up with kids crosschecking their schedules and floor plans. And ooh, April's still mad at Becky!
Panel 4: Awful, awful, AWFUL hair! She looks like DJ on the first seasons of Roseanne.
Panel 5: Now how the hell could she not have noticed Becky sitting there? She either walked towards her desk, in which case she would have seen Becky face to face, or she would have come up the aisle behind it, in which case she would have walked past her. Oh wait: perhaps Becky snuck in there in the time it took April to take off her cardigan. (Also, would she really be wearing the cardigan on the first day of school? I recall September as being pretty much unbearable in a t-shirt, let alone a blouse and sweater.)
Plus, that "history" gag has been done before, on Liz's first day in high school. Either she or Dawn said, "Everything we did last year is history!" and Miss Edwards said, "Actually, I think I get you for math!" as she wheeled up to them.