Chicago Public School once had a high-stake testing started from 1996. Put it simple, high-stake testing determined not only students' ability, but also the school's ability too. Schools with low reading mark will be given trial time or will be closed and the staff will be dismissed.
Well then, it gave the poor-in-grade schools' teachers the chance to cheat, so that they wouldn't be dismissed. Levitt here shows us how the teachers cheat.
And to find the similarities of teachers and sumo wrestlers...you might want to read facts about sumo wrestlers first. Turns out that sumo wrestlers can also cheat too to win the games. They got grades too and the wrestlers who achieve higher grades will be served things by the lower-graded ones. So then, it triggers the lower grade wrestlers to cheat, mostly by paying bribes.