As Strepsiades turns to enter the school, the Chorus of Clouds sings him a valediction and then turns to address the audience. The Chorus attacks the audience for not supporting the play in its earlier festival run. They recount Aristophanes's success with previous plays and paint a demure, deserving picture of Aristophanes's play: "My Comedy's a modest girl" (I.ii.547), a distraught maiden such as an "unwed mother" (I.ii.547) or "Electra" (I.ii.547) looking to reunite her family. The Chorus insist upon this "modest[y]" by claiming that Aristophanes never resorts to the gross physical and sexual humor to which other playwrights stoop. The picture the Chorus paints is of a long-suffering figure who has some vital, "new ideas" (I.ii.547) to present and who is standing by them in spite of persecution by "Cleon" (I.ii.574) or "plagiari[sm]" (I.ii.547). They insist that these "new ideas" are for the betterment of Athens and will improve the quality and character of the Athenian citizenship.
The Chorus of Clouds make a plea that the audience of Athenian citizens reconsider the play's worth and treat them justly—with respect, as they treat the gods. The Chorus ends its interlude by passing along a complaint from the "Moon" (I.ii.609) that the Athenians look to rectify their miscalculated lunar calendar, since their mishap has confused secular and sacred days and is causing cosmic chaos.
Socrates bursts out of the "Thinkery" arguing with Strepsiades who has proven to be a frustrating student. The two bicker. Strepsiades is unable to grasp much of what Socrates is asking of him. Socrates decides to teach Strepsiades about the gender of nouns: he introduces Strepsiades to the word "chickenness" (I.ii.658) for female chicken and "triffen" (I.ii.658) for a feminine trough. Even this lesson proves too much for Strepsiades. Disgusted, Socrates demands that Strepsiades get into bed and think about the lesson. The bed is flea-ridden and Strepsiades writhes, unable to properly philosophize. But he is not so incapacitated that he cannot masturbate, which he does.
Socrates and Strepsiades consider how to best avoid Strepsiades's debts. Strepsiades concocts amazingly fanciful plots—stopping time with sorcery, destroying evidence, and finally suicide—as a means to escape his predicament. Socrates declares that Strepsiades is a hopeless failure and storms off. Strepsiades appeals to the Chorus of Clouds. The Chorus suggests that Strepsiades enroll his son Pheidippides in his place. Strepsiades runs off. The Chorus turns conspiratorially to Socrates and encourages him to take advantage of Strepsiades.
Strepsiades hauls Pheidippides out of the house and raves to him about the wisdom and thrift of the philosophers at the "Thinkery." He enlightens his son to his new "atheism" and the proper gender of nouns. He is so wound up that Pheidippides thinks him mad. He drags Pheidippides to the school to meet Socrates. Socrates sizes-up Pheidippides and suggests a fee for his education. Strepsiades consents and Socrates calls forth two personified Arguments, Just and Unjust, to educate Pheidippides by their example.
Just and Unjust bicker and swap insults. Just defends the existence of the gods against Unjust's skepticism and blames Unjust for corrupting the Athenian youth and disrupting tradition. The Chorus of Clouds summons Just and Unjust to a formal debate over education and morality in order to decide how best to teach Pheidippides. Just speaks in support of the traditional educational system under which boys were obedient, respectful, and strong. Just's students are philosopher-soldiers and he swoons as he speaks, considering their beauty. After Just speaks, Unjust does not propose a different system, but rather cross- examines Just's statements according to examples drawn from myth and other items of trivia. Unjust's needling argument flusters Just, and Unjust wins the ability to teach Pheidippides. The Chorus of Clouds ends the act with an aside to the audience and festival judges, insinuating that the quasi-divine Chorus of Clouds will reward those who reward the Chorus, but that it will curse those who spurn the Chorus's obvious charms.