[Harry and Hermione see their past versions of themselves and Ron before Past Hermione punches Malfoy]

That's us. This is not normal.

This is a Time-Turner, Harry. McGonagall gave it to me first term. This is how I've been getting to my lessons all year.

You mean we've gone back in time?

Yes. Dumbledore obviously wanted us to return to this moment. Clearly something happened, he wants us to change.