It's important to note here that IQ may be fairly immutable...
but IQ isn't "performance."
But IQ affects performance when the task at hand requires cognitive ability. And this is where people get uncomfortable.
When, schools fail to acknowledge that individual differences in IQ are real, the system fails the people it's supposed to serve. You can see this in NCLB's assumption that everyone can meet age/grade level expectations or the idea that "everyone evens out by third grade." Society fails in this regard when we promote the idea that "most people should go to college."
Some people need more time to master material. When you push them too fast, they can't learn and get permanently behind. No wonder they can't pass the high-stakes tests. This is just my speculation, but I expect that people in this situation can't develop in ways that are critically important --- not too mention the fact that many probably shut down and learn less than they would have if they'd just been allowed to slow down.
Some people need less time to master material. When schools force them to go too slowly, the same problems are created.
Finally, not everyone is smart enough for college. And this is okay, just like the idea that not everyone can earn a varsity letter is okay. Everyone has different strengths and weaknesses.
Yet we have a myth that college is essential, so colleges have to offer easier courses for less-bright students. Many people go to college to earn an arbitrary credential (the BA) that is (wrongly) seen as a qualification for many jobs.
The result is indebted people with degrees who haven't learned how to think critically and who don't find jobs that excite them. I've seen studies recently saying that the number of hours spent studying in college has been declining since the 60s. This is hardly surprising if lot of people who aren't smart enough are in college.
They don't have the ability. Many can't focus on English lit. for long, and many don't want to anyway. And besides, they're there for a credential and not out of curiosity or love of learning. This is
not okay.
I wish we'd use our "you must go to college!" energy to help people find what they're good at and encourage them in those directions. I stand by my statements that the world needs electricians or plumbers far more than it needs more marketing managers or sales reps.
