What the Dog Saw [130]
It’s only a crude measure, of course. A teacher is not solely responsible for how much is learned in a classroom, and not everything of value that a teacher imparts to his or her students can be captured on a standardized test. Nonetheless, if you follow Brown and Smith for three or four years, their effect on their students’ test scores starts to become predictable: with enough data, it is possible to identify who the very good teachers are and who the very poor teachers are. What’s more — and this is the finding that has galvanized the educational world — the difference between good teachers and poor teachers turns out to be vast.
Eric Hanushek, an economist at Stanford, estimates that the students of a very bad teacher will learn, on average, half a year’s worth of material in one school year. The students in the class of a very good teacher will learn a year and a half’s worth of material. That difference amounts to a year’s worth of learning in a single year. Teacher effects dwarf school effects: your child is actually better off in a bad school with an excellent teacher than in an excellent school with a bad teacher. Teacher effects are also much stronger than class-size effects. You’d have to cut the average class almost in half to get the same boost that you’d get if you switched from an average teacher to a teacher in the eighty-fifth percentile. And remember that a good teacher costs as much as an average one, whereas halving class size would require that you build twice as many classrooms and hire twice as many teachers.
Hanushek recently did a back-of-the-envelope calculation about what even a rudimentary focus on teacher quality could mean for the United States. If you rank the countries of the world in terms of the academic performance of their schoolchildren, the United States is just below average, half a standard deviation below a clump of relatively high-performing countries like Canada and Belgium. According to Hanushek, the United States could close that gap simply by replacing the bottom 6 percent to 10 percent of public-school teachers with teachers of average quality. After years of worrying about issues like school funding levels, class size, and curriculum design, many reformers have come to the conclusion that nothing matters more than finding people with the potential to be great teachers. But there’s a hitch: no one knows what a person with the potential to be a great teacher looks like. The school system has a quarterback problem.
3.
Kickoff time for Missouri’s game against Oklahoma State was seven o’clock. It was a perfect evening for football: cloudless skies and a light fall breeze. For hours, fans had been tailgating in the parking lots around the stadium. Cars lined the roads leading to the university, many with fuzzy yellow-and-black Tiger tails hanging from their trunks. It was one of Mizzou’s biggest games in years. The Tigers were undefeated and had a chance to become the No. 1 college football team in the country. Shonka made his way through the milling crowds and took a seat in the press box. Below him, the players on the field looked like pieces on a chessboard.
The Tigers held the ball first. Chase Daniel stood a good seven yards behind his offensive line. He had five receivers, two to his left and three to his right, spaced from one side of the field to the other. His linemen were widely spaced as well. In play after play, Daniel caught the snap from his center, planted his feet, and threw the ball in quick seven- and eight-yard diagonal passes to one of his five receivers.
The style of offense that the Tigers run is called the spread, and most of the top quarterbacks in college football — the players who will be drafted into the pros