Our brains serve us well, remembering that tigers are fierce and blue-black berries are poisonous.

But our brains fool us.

We lock down on stereotypes: all tigers are fierce. All blue-black berries are poisonous.

And we do that with people, too.

When we learn that a student is smart then we expect him to wax brilliant and earn As.

And when we think a student is a slacker, we have a stack of C grades standing by.

When scientists tested teachers, they discovered when we think a student is smart, we grade accordingly.

If we judge a student as lazy or dumb, we grade accordingly.

Even if the paper we’re grading for each student is the same paper. That’s what scientists have found.

Now I face a new dilemma.

For years my students write secret numbers on their papers—not their names—so that I grade fairly and resist judgments. I trick my brain.

This week a student was peeved because she was reduced to a number.

She’s afraid I will treat her as a number, not a person.

She’s right, of course. All students in my class deserve to have their identities preserved.

But when it comes to grades I continue to use blind methods, knowing that sometimes blue-black berries turn out to be delicious.