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The planet race

Grades K–2 · 20 minutes · Observe it. The driving question: Why does everything out there orbit — and why don't the planets fall into the sun? Every step below is a link that opens the exact view — one link puts the projector and every student screen on the same sky. Part of the lesson plans by topic and grade.

Before the lesson — what this assumes

Assumes nothing — this works as the first space lesson of the year.
Optional pre-work, at home or in a spare five minutes: open the solar system simulator and just press Play. Wandering around it first makes the race feel like a place they've been.

The plan — every step carries its minutes

Warm-up · 3 minAsk who can name a planet. Count how many the class can name together, then open all eight at once on the projector and count the real answer.

Task 1 · 6 minOpen the four inner planets with a year on the slider and press Play. It's a race. Ask: who's winning? Let them shout it — then ask the only question that matters: what does the winner have that the others don't? (It's nearest the sun.)

Task 2 · 5 minCount together: how many times does Mercury go round while Earth goes round once? (Four.) Every lap of Earth's is one whole year — a birthday.

Task 3 · 4 minOpen the Earth and its moon — the one picture where the sizes and the distance are both true. Ask: which dot do we live on? Where is everything else? (Empty. Space is mostly empty, and that surprises everyone.)

Wrap-up · 2 minThree things on the board, in their words: the planets go round the sun; they never bump; the closest one moves fastest.

The minutes are there for the teacher's pacing — and so that any single step can be handed to a student as their own five-minute lesson. See students teach the class.

What they should find — the teacher's key

Mercury completes about four orbits per Earth year — the class counts it live.
Nearest-the-sun and fastest are the same planet; the pattern holds all the way out.
On the to-scale view the Earth is a handful of pixels and the moon a dot — the emptiness is the lesson.

Standards: Builds toward 1-ESS1-1 (patterns of objects in the sky).

What the picture fakes: On every system view the planet dots are drawn far larger than scale, and where each moon sits along its orbit is illustrative — sizes, distances, speeds and directions are real, positions are not solved, and the pages say so.

Questions to chase on your own

For the student who wants more — each answerable with the tools, no teacher required:

Which planet would you most want to visit? Open its page with a grown-up and find one thing about it nobody in class said.
Watch the race again at home: does the same planet always win?

Questions the curious actually ask

Real questions, mostly from real kids — the kind that sound simple and open trapdoors. Worth raising in class before someone raises them for you:

If gravity pulls everything, why doesn't the moon fall on us?
Here's the secret: it is falling — right now, continuously — and missing. The moon moves sideways so fast that by the time it has fallen toward Earth, the Earth's surface has curved away beneath it. An orbit is a fall that never lands. Newton figured this out by imagining a cannon on a mountain firing faster and faster until the cannonball fell all the way around the world — and that thought experiment is every satellite, the space station, and the moon.

Why don't the planets ever crash into each other?
Mostly they can't — each is locked in its own lane by its own speed, and the lanes are separated by distances that make the planets themselves like grains of sand miles apart. But here's the part worth knowing: early on, they did crash. The leading theory for where the moon came from is a Mars-sized world hitting the young Earth. The quiet, orderly system in the simulator is the survivor of a demolition derby — the orbits you see are the ones that lasted.

How does the sun keep burning? There's no air in space!
Because it isn't burning — fire needs air, and the sun would have burned out in a few thousand years if it were a bonfire. The sun is crushing: its own gravity squeezes its core so hard that hydrogen atoms fuse together, and fusion releases millions of times more energy than fire. It has run this way for 4.6 billion years and is about halfway through its fuel. Nothing is on fire. Something much stranger is happening.

Go further — beyond this site

NASA Space Place: All About the Planets — one illustrated page per planet, written for exactly this age.
ESA Kids — short animations and activities for early primary.

Same question, other grades

Each grade band re-asks this topic's question one level deeper — observe it, describe the pattern, measure it, explain the mechanism, quantify it and question the model. This page is the observe it rung.

Grades 3–4 Grades 5–6 Grades 7–8 High school & up All lesson plans

Teachers: make this lesson better

You are the one standing in front of the class, so you will see what we cannot: a task that runs long, a question that lands better another way, a grade level pitched wrong, a topic we should build next. Tell us — improvements go into the page, and if we use yours, your class gets the credit on it, the same promise the classroom request form makes.

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