Mix, pair, then share
In a Mix-Pair-Share, learners move around the room until a signal, then pair with the nearest person. The teacher poses one prompt; partners solve it and share their reasoning and answer; then learners mix again and pair with someone new for the next prompt. Moments are best learned this way: by talking through many short balancing problems with different partners.
It passes the PIES test:
Each prompt is solved as a pair, and both partners must be ready to share the reasoning.
Every learner explains a solution to a new partner each round, so no one can hide.
Partners change every round, so learners explain to and learn from many others.
At any moment half the class is explaining and half is listening.
One prompt per round
Learners move around the room while music or a signal plays.
On the signal, each learner pairs with the nearest person.
The teacher poses one prompt; partners solve it and share their reasoning and answer.
Learners mix again and pair with someone new for the next prompt.
Reveal one at a time
Five prompts of increasing difficulty, from reasoning to an angled force.
A door handle is fitted far from the hinges. Explain, using moments, why this makes the door easier to open.
A seesaw balances with a 200 N child 1.5 m from the pivot. Where must a 300 N child sit to balance it?
Explain why a longer spanner makes it easier to undo a tight nut.
A beam balances with a 5.0 N weight 0.60 m to the left of the pivot and an unknown weight 0.40 m to the right. Find the unknown weight.
A force of 12 N is applied at the end of a 0.25 m lever at 40 degrees to the lever. Find the moment about the pivot.
Teacher answersclick to reveal
placing the handle far from the hinges gives a large perpendicular distance, so the same push gives a larger moment and a greater turning effect, making the door easier to open.
200 × 1.5 = 300 × d, so 300 = 300d and d = 1.0 m from the pivot.
a longer spanner increases the perpendicular distance, so the same force produces a larger moment about the nut, making it easier to turn.
5.0 × 0.60 = W × 0.40, so 3.0 = 0.40W and W = 7.5 N.
moment = 12 × 0.25 × sin 40° = 12 × 0.25 × 0.643 = 1.9 N m.
When the room does not behave like the plan
The same learners keep pairing: call a longer mix, or have learners raise a hand until paired with someone new.
One partner does all the talking: ask the listener to report the reasoning back to the class, so both must follow it.
A reasoning prompt gets a one-word answer: insist on the moments language, "larger perpendicular distance, larger moment".
Limited space to move: learners can rotate within rows; the key is a new partner each round.
- Support: give a labelled beam card so a pair can mark forces, distances and turning sense before calculating.
- Challenge: add a prompt where the beam is not pivoted at its centre, so its own weight produces a moment.