Topic Library
Every lesson, on four shelves. Each one has something to build, click, or test yourself on.
Foundations
How do we know anything at all?
The Physical World
How do matter, energy, and space behave?Chemistry
Chemistry Atoms: The Building Blocks
What atoms are made of, how to read an element, and the difference between atomic number and mass number.
Chemistry The Periodic Table
How the periodic table is organised — periods, groups, metals and non-metals — and how to read a single cell.
Chemistry Molecules & Bonding
How atoms join into molecules — covalent vs. ionic bonding — and why a water molecule bends.
Chemistry States of Matter
Solids, liquids and gases at the particle level — and what really happens during a phase change.
Physics
Physics Gravity & Orbits
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.
Physics How Tides Work
Why the sea creeps up and slides back twice a day: the Moon's stretching pull, the two ocean bulges, and how the Sun makes spring and neap tides.
Physics Energy: Making Things Happen
What energy is, the two big kinds — moving and stored — and the golden rule: energy never disappears, it only changes costume.
Physics Light & the Universal Speed Limit
What light is, how mind-bendingly fast it goes, why nothing can ever go faster — and why looking at the stars means looking back in time.
Physics Black Holes: Where Gravity Wins
Put your three keys together — gravity, energy, and light — and open the strangest door in the universe: the place where not even light can pay the exit bill.
