 In the Homicide unit, Bunk is reading a book written by Laura Lippman.Lippman is a Baltimore resident, and is married to series creator David Simon.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.