How a course gets written for one reader

Most learning tools start from a catalogue. You pick the course that is closest to what you want, and then spend the first third of it on material you already know and the last third lost. Basis Lab starts from the other end: you say what you want to be able to do, it finds out where you are, and the course is written from there.

Here is what actually happens.

You say what you want to be able to do

Not a subject, an outcome. "Understand how attention works well enough to read the paper" is a better brief than "transformers", because the second one has no end in it. The goal decides what the last lesson is, and everything before it is chosen to get you there.

It finds out where you are

A short placement follows. It is not a test with a score at the end, and nothing is withheld on the strength of it. It exists to settle a handful of questions that change what the first lesson can assume: whether you are comfortable with the notation, whether you have met the prerequisite ideas, whether you can read code in the language the subject is usually written in.

This is the part that a catalogue cannot do. Two people asking for the same subject get different first lessons, because one of them needs the chain rule said out loud and the other has used it for years.

You get a plan, and you can change it

Before anything is written at length, you see the shape of the course: the lessons, in order, each with what you should be able to do at the end of it. If a lesson is beneath you, take it out. If something is missing, say so. The plan is saved on your account, so you can leave it and come back to it.

This step exists because the cheapest moment to fix a course is before it is written.

Then the lessons are written

Each lesson is a page you read, with figures drawn for that lesson and practice made for that lesson. Two things about it are worth naming, because they are the reasons the lessons are written down rather than delivered as a conversation:

1. 1

   Any sentence can be opened

   Select a phrase and ask about it, and the answer arrives beside it rather than in a separate conversation that scrolls away. You can keep going as deep as you like without losing your place on the page.

2. 2

   The page is still there tomorrow

   A chat that explained something well on Tuesday is a chat you have to find again on Friday. A lesson is at an address, with your notes and your answers on it.

And then it adapts

Every problem you answer tells it something, and that is the point of marking them properly rather than taking your word for it. The next lesson is shaped by what the last one showed: more practice on what you got wrong, less time on what you clearly have, and a sentence written differently when the first version did not land.

Why read a written course at all

Because a conversation optimises for the next reply, and a course optimises for what you can do at the end. Those are different jobs. A chat window will happily answer forty questions in a row without ever telling you that the thirty-ninth one was the important one, or noticing that you have not actually done anything yet.

If you would rather see the output before giving anybody a goal, the library holds 80 courses written this way, and the first lesson of each is readable without an account.

The first course you ask for is free from beginning to end, with no clock on it. After that it is $19 a month or $99 a year.