Nice breakdown of the mathematics of grading from WIRED.

As a physics faculty, I have two jobs. The first is coach. I help students wrestle with concepts and ideas. That makes me something like Gregg Popovich of the San Antonio Spurs, but with more equations. I’m also an evaluator. I determine how well students understand the material I’ve taught them. Yes, I find it odd that I do both of these things. It’s like having Popovich coach the team and referee the game. But that’s how it is in education.

Usually, I use this space to talk about my helping students understand physics. (Or I ponder important questions like whether Spider-Man can jump onto a ferry or Han Solo can survive light speed.) Today, I want to talk a little about evaluation—or what you might call “grading.” If you think about it, there are three methods you can use here. Which method you use depends upon how you view the concept of “grades” and what you think about student populations.

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