Mohammed was in another of my math classes last year. Unlike Tre, does not communicate his mental disability immediately. He talks quickly, cracks decent jokes, likes people around, while Tre was happier off in a corner listening to music. It took me a while to realize that Mohammed, who is neither black nor Hispanic, wasn’t retaining any information at all. Once I did realize this, I looked more closely at his IEP and saw he was a special day students with an IQ in the mid-80s. Also an excellent athlete, but very different from Tre. No fact grasp at all. He couldn’t remember what you told him five minutes ago, much less yesterday. But he could solve a simple algebraic equation with a calculator. He’d have to relearn it almost every day, but he had the ability to abstract that Tre lacks. He very badly wanted to move on to the next math class in the sequence, against the recommendation of his special ed adviser, and nagged me constantly to support him in this quest. I was willing to help him try, but his sport kept him out of the classroom a couple days a week for nearly a month, and everything I’d managed to do to keep him not rolling backwards was undone. So I passed him and talked him into an easier course.
The point is this: Tre and Mohammed, while not obviously or actually “dumb as a box of rocks”, as Smith indelicately put it, were noticeably less able than almost all my other students in five years, despite considerable motivation on their part and a huge amount of support on mine. I have probably had a couple other students with as low intelligence, but couldn’t be sure because they were never around or made class miserable by misbehaving. This suggests to me that my rough approximation of my students’ cognitive ability is correct. I haven’t taught many kids with IQs south of 90, and most of them my lowest IQ kids were in my Algebra I classes.