The link you share with the class for the 20 minutes online.
COMING SOON
MAIN THEME
Gravity is the weakest of the four fundamental forces, yet without it there would be no planets, stars or galaxies. Every time a learner picks something up, their arm beats the pull of the entire Earth.
BY THE END OF THIS SESSION, LEARNERS SHOULD BE ABLE TO
State that gravity is a universal force generated by anything that has mass.
Apply the two rules of gravity: more mass means stronger pull; greater distance means weaker pull.
Explain why planets and stars are spherical, using the idea of the equal squeeze.
Describe how the Moon acts as a gravitational brake on Earth's rotation.
Reflect on what would change on Earth without the Moon's gravitational influence.
Teacher tips
These are the notes from teachers who have run the session.
Hook
Most classes choose 'everyone flying into space'. It's worth asking learners what would actually push them upwards, because there isn't anything. That usually gets them to C on their own rather than being told.
If the room lands unanimously on one option, pick someone and ask them to argue for a different one. The reasoning is what you're after.
Flag early that gravity is the weakest of the four forces. Learners resist this because it doesn't match how it feels, so give them the image now rather than in the debrief: every time you pick something up, your arm beats the pull of the entire planet.
ITZA platform
Pathway 2's distance rule is the bit that gets skimmed. If someone's moving fast, ask what happens to gravity when you double the distance. 'Half' is the wrong answer nearly everyone gives first - it's better caught here than in the activity.
Anyone watching the film should explain the equal squeeze in their own words before they move on. Learners can repeat the phrase without having pictured it, and if they can't say what's doing the squeezing they haven't got it.
Classroom activity
Encourage learners to re-read each scenario carefully before committing to an answer. Most wrong answers come from fixing on one word, distance or mass, and missing the other, not from mishearing either one.
Throughout, emphasise that gravity is always relative, determined by distance and mass.
Encourage learners to come up with their own relative gravity scenarios to pose them to each other and/or the class. This can trigger some interesting debate around relative mass of objects.
Plenary
The reflective question is a good one for learners who find 'what did you learn' hard, because it's a scenario rather than a recall. If someone's stuck, ask what would happen when they tried to stand up.
Expect answers about heavier objects and nothing about the atmosphere, tides or the Moon's orbit. If that happens, ask what else on Earth is being held in place by gravity.
For the lock-in quote, allow learners to spend a few seconds digesting and processing it. Encourage reflections on that quote.
Misconceptions to watch for
THEY'LL SAY
"Astronauts float because there's no gravity in space."
ACTUALLY
Gravity in low orbit is still close to 97% of Earth's surface pull. Astronauts float because they are in constant freefall, orbiting so fast that they miss the Earth.
THEY'LL SAY
"Heavier objects fall faster than lighter ones."
ACTUALLY
Without air resistance, mass makes no difference to how fast an object falls. A feather and a hammer dropped on the Moon hit the ground at exactly the same instant.
THEY'LL SAY
"Gravity only pulls things down."
ACTUALLY
'Down' just means towards the centre of Earth's mass. Gravity is mutual; it pulls everything with mass towards everything else. The Earth is also being pulled slightly toward you.
THEY'LL ASK
"Why isn't an asteroid round like a planet?"
ACTUALLY
It takes enough mass for a body's own gravity to overpower the chemical bonds of the rock, pulling it into a sphere from all sides—the 'equal squeeze'.
Extension tasks
INVESTIGATE
Escape Velocity
How fast must a rocket travel to break completely free from Earth's gravitational embrace? Explore the formulas and the engineering requirements for deep space exploration.
Investigate how a change of just a few thousand miles in distance impacts the Moon's gravitational pull, altering high-tide indicators across coastal regions.
