Chapter 31 - "O.W.L.s" - In which Harry and Hermione tell Ron about Grawp, the fifth years take their O.W.L.s, Hagrid is sacked, McGonagall is stunned, and Harry dreams that Sirius is being tortured.
The Quidditch Final and Grawp
Harry and Hermione follow Hagrid into the [Forbidden Forest], where they finally learn what's been giving him injuries - his giant half-brother, Grawp. He then asks, in the event that he's sacked, that Harry and Hermione carry on teaching Grawp English and keeping him company, driving them to near hysterics.
On the way back from meeting Grawp, Hagrid has a run-in with the centaurs, who are furious with him but let him go only because he's with Harry and Hermione. Hagrid ignores them completely, though, and leads Harry and Hermione back toward the castle.
Walking back up to the castle, Harry and Hermione hear more choruses of "[Weasley is our King]," but their initial anger toward the [Slytherins] turns to surprise when they realize the lyrics are different - and it is instead the [Gryffindors] celebrating Ron's leading them to a [Quidditch Cup].
After some coaxing Harry and Hermione finally convince Ron to join them outside - where they finally interrupt his celebrations over his [Quidditch] victory for long enough to tell them about Hagrid and Grawp. After some discussion, Hermione refuses to let Hagrid down, but Ron points out hopefully that the end of the term isn't far, and perhaps they can get through it after all.
Preparing for the O.W.L. Examination
After a year of warnings and preparation, [O.W.L.s] are finally approaching. Harry's nerves rise as [Ernie Macmillan] brags about his study time, Draco Malfoy suggests that connections are what earns top scores (though Neville doubts his bragging), and fake brain stimulants start making the rounds among fifth years.
In the final [Transfiguration] class of the year, McGonagall passes out [O.W.L.] exam schedules and announces that scores will be sent in July.
At dinner the [O.W.L.] examiners arrive, making everyone even more nervous as [Umbridge] begins to show them around and [Professor Marchbanks] asks about [Dumbledore].