Hagrid arrives, asking Harry not to speak Voldemort's name and updating Harry and Ron about Grawp. As he walks away, Harry and Ron realize that nobody will be taking [N.E.W.T.]-level Care of Magical Creatures.
Late to the Welcoming Feast
[Dumbledore] makes his usual Welcoming Feast announcements, about banned items and safety, and also a new development - Snape will be taking over as Defence Against the Dark Arts professor, while Slughorn teaches Potions.
Chatper 9 - "The Half-Blood Prince" - In which Gryffindors get course schedules and discuss Malfoy and Quidditch trials, then go to their first day of classes. In Defence Against the Dark Arts Harry fights back against Snape's attempt to jinx him and gets detention, during break he hears his first lesson with Dumbledore will be Saturday, and in Potions Harry wins the Felix Felicis thanks to a perfect potion he brewed with the instructions written in his book by the Half-Blood Prince.
Harry and Ron tell Hermione about Draco Malfoy's conversation on the train, Hermione confiscates a Fanged Frisbee (which Ron takes, much to Lavender Brown's amusement]), and they discuss their new schedules.
Business at Breakfast
Snape's Defence Against the Dark Arts Class