As Wallace helps one of his young charges with their math homework, Poot shows up and asks him to return to work.
Wee-Bey, Stinkum and Savino raid Omar's apartment and torch his van while he watches from his hiding place across the street.
The soldiers throw a party celebrating Stinkum's promotion, which will be official as soon as they kill a dealer named Scar and chase his crew off his corner.
McNulty briefly loses sight of his sons, but they manage to write down Stringer's license plate number.
Based on information gleaned from the wire, they pull over Senator Davis's driver, Damien "Day-Day" Price, and find a bag full of cash in his car.
Because of Price's political connections, Burrell demands that his men return the money and tells Daniels he will shut down the detail.
Later, McNulty tails Stringer and discovers he is taking an economics class at Baltimore City Community College.
McNulty tells Bunk that Omar was the shooter and asks him to tell Cole they will give him a closed case once their case is finished, but acknowledges that because of Omar's assistance, he will not ultimately deliver him to Cole; both men regret the lie and go out drinking to soothe their consciences.
Later, McNulty is called by the woman to come and collect Bunk, who is so drunk that he decided to burn his clothes to destroy the evidence of his infidelity.
The title refers to the classes Stringer takes, Wallace teaching the math problems to the child in his charge, Judge Phelan showing his control over Burrell to McNulty, the sergeant's exam Herc and Carver take, Freamon teaching Kima about the use of instinct in solving cases, Kima learning that she made an error on the Omar witness case, and Omar teaching a lesson to the Barksdale soldiers.