Basis Lab blog

On learning the hard subjects.

What a tutor can do that a chat window cannot, how a course gets written for one reader, and the parts of the mathematics that keep tripping people up.

• Building in public20 Oct 20265 min read

  We assumed the mathematics, and that was the wrong assumption

  The library started at attention and backpropagation, which is where the interest is. Nineteen courses later it starts at what a letter is standing in for, and the reason is worth writing down.

• The subject itself20 Oct 20266 min read

  Six growth shapes, and the one column worth memorising

  Almost all work falls into a handful of shapes, and the useful question about each is what happens when the input doubles. That one sentence decides most design arguments before they start.

• The subject itself20 Oct 20267 min read

  The notation nobody teaches you, and the thirty marks it is made of

  Most people who stall on a formula have not failed at mathematics. They were never given the vocabulary the page assumes: what a letter is standing in for, which letters are local, and where the declaration hid.

• Product20 Oct 20266 min read

  What is actually in the library: 80 courses, 640 lessons

  A tour of the ten shelves, what each one is for, and what you can read without an account.

• Product20 Oct 20266 min read

  Five reading orders through the library, and how to pick one

  Eighty courses arranged by subject answer the question "what is this about". The five tracks answer a different one: what will I be able to do when I finish, and what should I read first.

• How it works20 Oct 20267 min read

  How your work gets marked, and where we admit we cannot

  Six kinds of practice, decided by instruments wherever an instrument exists: tests run one at a time, working checked line by line, and an honest label on the cases only a model can judge.

• Comparison20 Oct 20266 min read

  An AI tutor is not a chat window

  A general assistant can explain anything you ask about. What it cannot do is decide what you should be asked, notice that you have not done any of it, or remember next week what you were shaky on.

• How it works20 Oct 20266 min read

  How a course gets written for one reader

  What happens between saying what you want to learn and having eight lessons to read: the placement, the plan you can change, and why the lessons are written down rather than said once.