Courses

Every lesson is free to read. A course adds a quiz at the end of each unit, a final exam that is marked and then checked by a person, and feedback that shows the line where your working went wrong.

Graduate

Partial Differential Equations

Transport, heat, wave and Laplace equations, Fourier methods, energy and maximum principles, weak derivatives, Sobolev spaces, well-posedness and scaling.

7 units · 121 questions · graded final College

Calculus

Limits, derivatives, integrals and series: the single-variable calculus of a first university course.

8 units · 169 questions · graded final Graduate

Fluid Dynamics

From the continuum hypothesis to the regularity theory of the incompressible Navier-Stokes equations.

8 units · 131 questions · graded final

How a course works

  1. Read the lessons in order. They are the same free lessons as the rest of the site, grouped into units.
  2. Take the quiz at the end of each unit. It is marked the moment you submit, with the worked solution for every question. The first unit's quiz is free.
  3. Pass every unit and sit the final. Answers the algebra system can check are marked by it; written proofs and photos of your working are read by a model and then reviewed by a person before your result is released.
  4. Wherever you went wrong, the result shows the line where it happened and why.

Prices

Course pass

$39

Every unit quiz, the final exam with one retake, and 20 checks of your own working, for one course.

One final exam

$15

A single sitting of one course's final, marked and reviewed. For someone who already knows the material and wants it tested.

Every course

$19/mo

All quizzes and finals in every course (two finals per course a month) and 100 working checks a month. Cancel from your account.

Working checks

$9

Ten checks: upload a photo of any working, or type it, and see where it went wrong.

Courses open for purchase soon. The lessons and the first quiz of every course are open now.