Topic Library

Every lesson, grouped by discipline. Each one has something to build, click, or test yourself on.

Foundations

How do we know anything at all?

How science actually works — observation, hypotheses, and what makes a question testable.

How do substances combine and change?

What atoms are made of, how to read an element, and the difference between atomic number and mass number.

How the periodic table is organised — periods, groups, metals and non-metals — and how to read a single cell.

How atoms join into molecules — covalent vs. ionic bonding — and why a water molecule bends.

Solids, liquids and gases at the particle level — and what really happens during a phase change.

How do matter and energy behave?

What gravity is, why the Moon doesn't fall down, mass vs. weight, and the speed you'd need to escape a planet's pull.

How does life work?

Where cats come from, how they evolved over millions of years, and how they (mostly) domesticated themselves by moving in with farmers.

How do planets, oceans, and stars work?

How a cloud of gas becomes a star, why some stars end as white dwarfs and others as black holes, and what mass has to do with it.