Everyone has heard stories about how math instruction has changed since today’s parents were in school - if not for the worse, then at least for the weird. These complaints represent a genuine phenomenon; math instruction really has changed. This perception has grown a great deal in the past decade as Common Core (RIP, more or less) and many state-specific curriculum reforms have pushed emerging pedagogical philosophies from academic journals into the classroom1. What’s going on?
First, we should distinguish recent changes from “New Math,” a somewhat-common reference point when I was young. Those changes, similar in the sense of being clumsily adopted with good intentions and pressure from above, took place several generations earlier than what I’m referring to now, mostly in the 1960s. It was all a big failure, at least in public opinion.
Here’s the nut of what’s been happening in the past decade. This evolution in teaching math in the United States stems from both a pragmatic problem and a theoretical justification. The problem is that math scores in the United States don’t improve in general and particularly don’t in middle and high school, when judged on a variety of metrics. (I refuse to say that American math skills are bad, as when we make responsible comparisons in historical and international terms they simply aren’t, but that’s for another time.) Many people have been vexed in particular by the failure of improvements in 4th grade NAEP scores to be matched when that cohort ages into 8th grade. (The kids by and large won’t be the same kids taking the tests, as it’s a sampled and stratified test, but for that very reason it shouldn’t matter.) There’s a 4th grade advantage in absolute terms; in 2019, 41% of 4th graders and 34% of 8th graders scored proficient in math in 2019. But there’s also been more difficulty showing year over year progress in 8th grade too. Here’s an elegant visual demonstration of the 4th vs 8th grade slowdown: