Sure! I tutored the majority of my classmates in Calc and Physics and I did not find one person I believed couldn’t do it. I did find a lot of people who believed they couldn’t do it, weren’t good at math, and wanted to give up though.

Some of the main problems:

* A lot more people than you would expect have attention issues and just needed someone to give them one-on-one attention. They would get distracted in class for a minute and then be lost for the rest of the lecture. I got permission from our teacher to record the lectures and then had people work through them with the advantage of a pause and rewind button.

* Some people were really independent and our textbooks were utter trash. I brought them “more advanced” books like Spivak ayyy that didn’t treat the reader as an idiot too stupid for a rigorous explanation. Having someone not “teach down” to them opened up so much. Easiest tutoring sessions ever when they just needed some quiet space to read. It’s amazing how much lack of understanding comes from years of teachers treating them as stupid and trying to have them memorize shortcuts that convey no understanding and don’t generalize.

* A few people were very tactile and so I brought in my laptop with Mathematica and had a bunch of examples coded up and let them play with the sliders. So many people groked limits and integrals with this.

* Some people needed more or less abstraction. Symbol overload is real. I loved saying something like “and this is true for any 17.” Connecting problems to “real life” wasn’t as effective as I had hoped but putting numbers in or having a variable cheat sheet they could quickly reference the meaning / value worked great!

* Some people learn by machine learning. They need a bunch of problems to work algorithmicly to feel the pattens. I called them numeric tactile. Once they’ve done it 50 times or so they’re ready to hear the abstract explanation because they’ve oriented themselves.

* A lot of people struggled because HS has so little focus on rote memorization. People didn’t have the toolbox of identities and little tricks at the forefront of their minds but some flashcards and cheat sheets fixed that right quick. I had like 5 people suddenly get trig identities once I made them memorize a few of the core ones. Constantly asking them to repeat something back to me whenever it came up was way more effective than I thought.

As you can clearly see I didn’t have much of a social life in HS.

Replying separately to the tutoring anecdotes, you reminded me of someone I tutored who was having trouble learning the chain rule. He got it after going through (with supervision) a single example I assigned - calculate the derivative of sin(sin(sin(sin(sin(x))))). At which point he rather angrily exclaimed "why isn't that example in the book?!"

I'm not quite sure what the connection is, but the combination of

> Easiest tutoring sessions ever when they just needed some quiet space to read.

> A lot of people struggled because HS has so little focus on rote memorization.

brought it back.

Your calculus and physics classmates are not a representative sample of people.

Sure, but I don't have any prior belief that my classmates -- kids around my age in my area which was lower-middle to upper-middle class depending on the neighborhood at a middling school -- skewed more proficient in math than the general population.

Of course it's not representative but I find it hard to believe that some no name school happened to be where the math nerds all hung out.

The population of students taking calculus in high school is already skewed more proficient than the general population just by that fact. (Obviously, the causality runs in the other direction, but the skew is there.)