Yeah, I definitely overstated the case in a fit of hyperbole. I find that when I read content on teaching math from people who have a constructivist inclinations (like me), there is a lot of emphasis on open ended problems and exploration. I even find a lot of techniques for wrapping up and ensuring that the key ideas from a lesson were grasped by all students (this is an area where I see many constructivist classrooms struggle).

But I don’t have a ton of advice for the kind of scripted independent repetition that I see as analogous to doing scales on an instrument or to doing drills in a sport. When I learn things, I definitely benefit from this kind of repetition over time as an antipode in the cycle to building my conceptual understanding. The fluency I get from the repetition gives me access to the conceptual work. I see Khan Academy as a great tool for enabling students to take some amount of independent responsibility for their practice. They primarily use the exercises to do this, but can also rely on the videos to refresh algorithms. This allows me, as a classroom teacher, to support exploration in building conceptual understanding. I think this is the primary overarching model of instruction that Salman Khan and his team envision for classrooms using Khan Academy. That said, in the Khan Academy content, they present many different models:
https://www.khanacademy.org/khan-for-educators/getting-started-teacher-training-us/implementation-strategies-us/classroom-strategies/a/introduction-to-using-khan-academy-in-the-classroom

Much of the writing on progressive/constructivist education takes for granted the importance of practice.

Geez, well I don’t know about that, but I appreciate the illustration of how KA supports your work as a teacher.

It allows me, as a classroom teacher, to have three act task style lessons and to give time for students to explore why it works and how you know. I agree with your critique about the teacher tools, but they improve significantly each year. And they are free which really matters.

A growth opportunity, in my opinion, is more effective tools for differentiation and supporting students with very diverse needs. At dinner school this year I had a couple students who really didn’t understand the idea of making ten and certainly didn’t know their addition facts to make tens. They required weeks of work on arithmetic to support work with variables which were terrifying. In the same classroom I had other students who were relatively confident with algebra 1. Khan Academy was very helpful but did not provide enough tools for supporting me in determining what skills students needed support with. By the end, the struggling students were able to build strong foundations on the number line and to turn fraction addition and subtraction into something more than rote algorithms (mostly applied incorrectly). I think we could’ve made more progress with better tools for tracking students student mastery.