KINDERGARTEN — the sky above us.
The very first steps: what the Sun, Moon and stars actually are, and why day turns into night, written for a 4–6 year old (or a grown-up reading aloud).
In a nutshell
After this stage, a learner can point to the Sun, Moon and stars and explain why day turns into night.
PRIMARY / ELEMENTARY — our solar neighbourhood.
Ages roughly 7–10: the eight planets in order, why the Moon changes shape, and how to find your way around the night sky.
In a nutshell
After this stage, a learner can list the eight planets in order and explain why the Moon's shape seems to change.
MIDDLE SCHOOL — the mechanics of the sky.
Ages roughly 11–13: why things orbit, what causes eclipses and seasons, and a deeper tour of the Solar System.
In a nutshell
After this stage, a learner can explain why objects orbit instead of falling, and what really causes eclipses and seasons.
HIGH SCHOOL — stars, light and galaxies.
Ages roughly 14–17: how stars live and die, how we decode starlight, the diagram that organizes all stars, and our home galaxy.
In a nutshell
After this stage, a learner can trace a star's life cycle on the H–R diagram and read basic clues from its light.
COLLEGE / UNIVERSITY — rigor at cosmic scale.
18+: deriving orbits from first principles, the nuclear physics inside stars, spacetime itself, the origin and fate of the universe, and the search for other worlds.
In a nutshell
After this stage, a learner can derive orbital motion from Newtonian gravity and explain the evidence behind an expanding, dark-matter-dominated universe.