Chapter 6 - "Glideroy Lockhart" - In which Ron receives a Howler, they learn about mandrakes in Herbology, Colin Creevey asks for an autographed photo, Lockhart is the new Defence Against the Dark Arts teacher, and they learn about Cornish pixies.

Harry and Ron's Glorious Start to their Second Year
Stuck in Snape's office, Harry and Ron are forced to try to explain their actions, first by Snape and then by McGonagall and [Dumbledore]. They are admonished, given detentions, and warned that farther misbehavior will warrant expulsion from Hogwarts. McGonagall then leaves them to eat dinner there before heading up to Gryffindor Tower.
Harry and Ron return to Gryffindor Tower, where Hermione lectures them but the rest of the Gryffindors celebrate their dramatic entrance.
Start of Classes
At breakfast, Ron recieves a Howler from Mrs. Weasley, making Harry feel awful. McGonagall then comes by with course schedules and the second years rush off to Herbology.
As Herbology class prepares to start, Harry notices Gilderoy Lockhart annoying Professor Sprout, and the class heads to Greenhouse Three with some interest.
Before Harry can get to Herbology, Gilderoy Lockhart pulls him aside, both admonishing him for showing off in the [flying car] and bragging about Lockhart's own accomplishments.
In Herbology class, the second years work on repotting [Mandrakes] and Justin Finch-Fletchley introduces himself to Harry.
In the year's first Transfiguration class Ron has some difficulty owing to his broken wand, while Harry feels like he's forgotten everything he learned in his first year.
At lunch Hermione shows off her coat buttons from Transfiguration class, and Ron notices she has outlined all of Lockhart's lessons on her schedule in little hearts.
Colin Creevey introduces himself to Harry and asks to have a photo taken and for Harry to sign it. Malfoy stops by to loudly make fun of Harry, and then to poke fun at Ron at the same time.