Anecdotal data point: My son is finishing 9th grade, and he's taking 10th grade math because he got ahead a year when he was younger. At his school, you're exempted from having to take the final exam if you're passing with a reasonable grade at the end of the semester. He said there are about four students who don't have to take the final exam.

Math has always been hard to teach well, because issues with earlier math classes compound so much. With all the societal interruptions to education, and the impact of addictive tech on young people's minds, it's only gotten more difficult.

True. COVID has set the entire cohort back, in terms of education but also every other aspect of personal development.