Chapter 7 - "Mudbloods and Murmures" - In which Harry begins Quidditch practice, words are exchanged with the Slytherin team, Ron's spell backfires, Harry and Ron serve detention, and Harry hears a voice.

Start of Classes
After he overhears Malfoy's taunt about signed photos, Lockhart once again pulls Harry aside to discourage him from seeking publicity, signing a picture for Colin in the process.
Cornish Pixies
The second years enter for Defence Against the Dark Arts, where Lockhart gives them a quiz - on himself. He then unleashes Cornish Pixies, fails to control them, and runs out, leaving Harry, Ron, and Hermione to take care of the creatures.
As his first week back at Hogwarts passes, Harry works hard to avoid Lockhart and Colin Creevey, Hedwig is avoiding him, and Ron continues to struggle with his broken wand.
Quidditch Practice Interrupted
[Oliver Wood] unexpectedly awakens Harry for an early morning [Quidditch] practice. Harry sleepily agrees and gets out of bed to head downstairs.
Colin Creevey stops Harry on his way to [Quidditch] practice, pestering him endlessly with questions until Harry is finally able to ditch him to join the Gryffindor team in the [locker room].
[Oliver Wood] leads the [Gryffindor Quidditch team] through an exasperatingly boring lecture on strategy, and then out onto the [Quidditch pitch], where Ron, Hermione, and Colin Creevey are sitting, for the start of practice.
With the [Gryffindor Quidditch team] finally ready to begin practice, they are interrupted by the [Slytherin team], led by Draco Malfoy. Malfoy, rude as ever, insults all of the Gryffindors and calls Hermione a [Mudblood] - prompting Ron to jinx him. The jinx, though, backfires, and Ron begins belching slugs, so Harry and Hermione drag him away.
Slugs at Hagrid's Hut
As Harry and Hermione drag a slug-belching Ron to Hagrid's hut, they find Hagrid outside with Gilderoy Lockhart bragging about himself again.