One small box, and a shelf of good things to learn from.

Grant Sanderson's animated linear algebra, calculus and analysis. The reason a lot of people suddenly understood eigenvectors.

Physics and engineering questions taken seriously, often by going and measuring the thing in person.

Working mathematicians with a brown-paper pad, talking about the problem they actually find interesting.

Matt Parker doing maths badly on purpose, then well. Excellent on why a wrong answer is wrong.

Real proofs, worked all the way through, without pretending they are easier than they are.

Now mostly about how machine learning works; the older Imaginary Numbers Are Real series is still the best thing on complex numbers anywhere.

One person building electron microscopes and X-ray machines in a home workshop. What engineering actually looks like.

Small physical demonstrations that look impossible until the explanation lands. Very good at admitting when he was wrong.

Beautifully made overviews of big questions — scale, energy, biology. Start here, then go to a primary source.

Tomasz Rożek, a physicist by training, on current science and the Polish research behind some of it.

Space and astrophysics in Polish — black holes, missions, telescopes, and why none of it is boring.

Every physics lesson a lyceum teacher gave between 2014 and 2020, grades 7 to 11, recorded in full. A complete course, free.

Type a surface, spin it with the mouse. Nothing makes multivariable functions click faster.

The 2D one. Sliders turn every constant in an equation into something you can feel.

Geometry, algebra and calculus in one place, with a huge library of constructions other people have already built.

University of Colorado's physics, chemistry and maths sims. Free, translated into many languages including Polish.

Hundreds of small interactive physics simulations, built and still maintained by one retired physics teacher.

Draw a circuit and watch the current move through it as dots. Electronics stops being abstract in about a minute.

Ask it anything computable. Best used to check your own answer, not to skip getting one.

All three volumes, free to read online, hosted by Caltech. Sixty years old and still the clearest physics writing there is.

Actual MIT courses — lecture notes, problem sets, exams, solutions. Free, no sign-up.

The place to quietly repair a gap from two years ago before it breaks something new. Partly available in Polish.

Algebra through calculus III and differential equations, written plainly with worked examples and printable cheat sheets.

A hub of playable essays — epidemics, trust, segregation, evolution. Things you understand by fiddling with them.

Probability and statistics as interactive visuals. No longer updated, but it explains the central limit theorem better than most textbooks.

Mathematical problems that need a bit of code to solve. Problem 1 takes five minutes; nobody has finished them all.

Two programming puzzles a day through December, in any language. Genuinely the most fun way to learn to program.

Paste any integer sequence and find out whether mathematics already knows it. Strangely addictive.