Though a disaster, why did “New Mathematics” assist and boost some high school students suffering from ADHD and Dyscalculia?

I quote Prof. Andrew Lo’s classroom presentation on June 2 2023 at his alma mater, Bronx High School of Science, starting at 4 minutes 11 seconds ―

And people tell me that those students who struggled with ADHD, it’s along the same lines. You know, once you are diagnosed and you realize this is an issue and you’re able to treat it, it’s like WOW, I get it. So that’s what I went through and it was really transformative. It made realize there are lots of different ways of learning and that helped me later on in life and it also helped me with my own kids.

❶ This website doesn’t flesh out the peculiar success of “New Math” for dyscalculia students. Why exactly did “New Math” assist dyscalculia students to improve their mathematics grade from C to A, but not other students? This April 16 2025 interview with Sarah Hansen sheds a little more light, but still doesn’t answer my question.

And I think it was that experience that allowed me to get through my elementary years, despite the fact that other teachers that I had who were not so supportive-- were pretty discouraging to me and to my mother. Back then, there was no diagnosis of ADHD or dyscalculia. So, I basically soldiered on until I went to high school at that Bronx High School of Science I mentioned.

SARAH HANSEN: Because it was more analytical and less focused on—

ANDREW LO: Numbers. No numbers. To this day, I have a hard time memorizing numbers. I never memorized the multiplication tables. I still have trouble with 6 times 7. I have to actually do the calculation in my head. And it takes me a little bit longer than most people.

But when you replace numbers with equations, that was like a huge relief. It's like wearing shoes that are two sizes too small. [emphasis mine] And then you take them off, and you put on shoes that are just exactly the right size. It felt wonderful.

❷ Why does replacing “numbers with equations” yield a huge relief? How’s replacing “numbers with equations” at all related to “wearing shoes that are two sizes too small”? Lo’s simile discombobulates me!