Professor Snape gives Harry a hard time during the potions class (in the Sacristy). McGonagall introduces Harry to Oliver Wood outside Professor Quirrell's Defense from the Dark Arts classroom (in the Warming Room). The trio find Harry's father's name in the Quidditch trophy case. Later, Harry finds the Mirror of Erised in a storage room (in the Chapter House).
Harry sneaks into the restricted section of the library using his invisibility cloak. Later, Hermione finds information on the Philosopher's Stone while the trio is studying. Later, Harry wakes up in the infirmary where he is being watched over by Dumbledore.
Hagrid leads the trio and Draco deep into the forest at night where Harry sees something devouring a unicorn.
The trio heads to Hagrid's Hut to talk to him and later they have to return with Draco as punishment.