The secret of the D.A. makes Harry feel powerful, and makes Umbridge's Defense Against the Dark Arts classes bearable. He thinks about his classmates' progress--even Neville is improving. Hermione soon comes up with a method of communicating the next meeting time. She creates fake Galleons and bewitches them to show the date and time when Harry changes the numbers on his own. Everyone is impressed with Hermione, but Harry quietly points out that the Galleons remind him of the Death Eaters' Dark Mark tattoos, which Voldemort uses to summon them.
Harry's positive emotions surrounding standing up to Umbridge show that even quiet rebellion can be extremely effective at boosting morale—it's important that people feel like they're doing something, even if what they're doing is secret and subversive. Neville's improvement reinforces McGonagall's earlier assertion that with confidence, Neville can do as well as anyone else.
D.A. meetings almost stop in the lead-up to the first Quidditch match between Gryffindor and Ravenclaw. McGonagall declines to assign homework in the week before the match, while Snape ignores reports of Slytherins hexing Gryffindor players in the halls. Harry feels optimistic despite Ron's spotty performance, though he worries because Ron seems to take the Slytherins' taunts seriously. On the morning of the match, Ron looks ill. Harry tries to make Ron eat breakfast as Ron insists that he's a horrible player. Luna walks up behind Harry and Ron wearing a huge lion-shaped hat that roars to wish them luck.
Ron hasn't spent the last four years dealing with Slytherins' taunts in the lead-up to Quidditch matches, while Harry has. Because of this experience, Harry is better able to block out the taunts. This also translates to how Harry deals with the Ministry's attempts to discredit him. While it still gets to him, Harry has more practice dealing with so much negative attention and presumably handles it better than someone like Ron would be able to.
A few minutes later, Harry leads Ron to the changing rooms. Hermione whispers to Harry that he shouldn't let Ron see the Slytherins' badges, but Harry notices that they say, "Weasley is our king." Angelina notes that the new Slytherin Beaters are Crabbe and Goyle, and Harry assures her that they're unintelligent brutes. On the field, the entire Slytherin team is wearing the badges, but the game begins with little fanfare. Lee Jordan pauses his commentary to point out the song the Slytherins are singing, which says that Ron is their king because he's a terrible Keeper. Realizing what the song is about, Lee shouts even louder.
The song "Weasley is our King" acts as a foil of sorts for the D.A. It shows how effective simple things can be at riling people up and making people feel like they're doing something to help their side. The fact that they even have badges to match the song shows just how thorough Malfoy and the other Slytherins can be in their cruelty.
Harry watches with horror as Ron lets the Slytherins score three times. Seeing the Snitch, Harry dives, hits Malfoy's hand out of the way, and grabs the Snitch. A Bludger hits Harry in the back, knocking him off his broom. Malfoy lands nearby, and as the Gryffindor team lands, he angrily shouts that he wanted to write more verses insulting Mrs. Weasley and Mr. Weasley. Harry tries to hold back George as the rest of the team restrains Fred, but when Malfoy insults Lily Potter, Harry and George rush Malfoy and punch him. They stop when Madam Hooch jinxes them and sends them to McGonagall's office.
Fred, George, and Harry's attempts and successes in hurting Malfoy for insulting their families again shows how easy it is for someone like Malfoy to weaponize an enemy's love for others to incite them to action that feels good and righteous, but isn't the best idea in practice. Given what the reader knows of McGonagall, however, the reader, Harry, and the twins can trust that she'll be fair, if possibly harsh.
Enraged, McGonagall shouts at Harry and George, but she stops short when Umbridge steps in and offers to "help." McGonagall refuses and gives both boys detentions, but Umbridge pulls out a new Educational Degree that gives her the power to punish students however she sees fit. She bans Harry, George, and Fred from Quidditch and insists they hand over their brooms so she can lock them up. It barely feels like Gryffindor won the match. Hermione and Harry are the last ones in the common room when Ron steps through the portrait hole. He says he's going to resign as Keeper but yelps when Harry tells him the news. Ron takes responsibility for letting the song get to him. Hermione, standing at the window, says that Hagrid is home.
Though Umbridge is successfully taking control over the school, she also should be aware that she just gave Harry a lot more time to think up ways to resist her that were once taken up with Quidditch practice. Though Umbridge has many powers and tools at her disposal, she's also under the impression that someone like Harry is going to let her get away with what she's doing. She knows that Harry hates her, but underestimates his (and Hermione’s) intelligence at undermining her in quieter ways.