Find your way through physics, mathematics, chemistry and materials science.

A bilingual reference and practice site, built subject by subject.

Start with the roadmap Browse the formula index

How it works

Every formula, generated fresh

Practice problems are generated from parametrised templates with a new seed each time, graded instantly in your browser — no two attempts look the same, and there's no server round-trip waiting on you.

Learn at your level

Every concept is tagged from lower secondary through bachelor core, so you can filter the roadmap to exactly the depth you need and see what each concept unlocks next.

Two languages, one glossary

English and Estonian ship side by side for every concept, with Estonian physics terminology locked against a cited glossary — not machine-translated, and never missing a locale.

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The mole and amount of substance

The mole is the SI unit for counting particles, defined so that one mole of any substance contains the same number of entities — which lets a mass measured on a balance be converted into a count of atoms or molecules.

Algorithms and program structure

An algorithm is a finite, unambiguous sequence of steps that solves a class of problems; a program is one expression of an algorithm in a language, and the same algorithm can be written in many languages.

Structure and properties

A material's useful properties follow from its structure at several scales at once — atomic bonding, crystal arrangement, defects and microstructure — which is why the same element can be soft graphite or hard diamond.

Complex numbers

Adjoining a number i whose square is −1 extends the real numbers to the complex numbers a + bi, in which every polynomial equation has a solution and arithmetic still works exactly as before.