A new study examined how tennis players improve. It cost $21 million.
It was an interesting approach. 195 players each got 68 hours of training. A control group got about 13 hours of training.
There were no drills, though. No actual practice hitting tennis balls.
Instead, the players sat in a room and listened to lectures about tennis swing mechanics. "Hard-to-grasp" concepts, like slice backhands and kick serves.
Each player was then observed one time. Did he apply what he'd learned in the lectures? Nobody actually got traditional tennis lessons, where you repeat the same stroke over and over and over, or where the coach picks your most obvious improvement area and yells at you while you play: "Racket Back Now!"
Okay, okay, that's not what happened.
Instead, they used this exact same approach to try to improve math teachers. Guess what? According to a giant federal study reported in Education Week: No effect!
I guess for just $108,000 per teacher, we shouldn't expect any results.