1 - Getting Started ~3 mins
Three parcels have arrived for the class. The boxes are the same size. Can your eyes alone tell which is heaviest?
2 - Watch and Notice ~8 mins
We guessed an order. Now the balance checks it, two parcels at a time.
When one pan sits lower, that side is heavier. That is the tip. After every tip we update our line on the board: lightest to heaviest.
Which pan is lower? Who is heavier? Our line so far: A, then B.
Which pan is lower? Who is heaviest? Full line: A, B, C.
When both pans sit flat, the two sides weigh the same.
Look back at our guess. Did the balance agree?
3 - Try It Together ~10 mins
Each pan holds one parcel made of cubes. Look which pan sits lower. The pupil at the board moves the cubes. After every tip, the class says the order together, lightest to heaviest.
Weigh a pair, update the order
4 - Write the Order in Your Copy ~3 mins
Look at the checked line on the board: A (5 cubes), B (8 cubes), C (11 cubes). In your maths copy, write that order, lightest to heaviest.
5 - Class Challenge ~8 mins
Weigh the parcels together. After every tip, say what the pans tell us — lightest to heaviest. Level pans mean the same weight.
Order by weighing
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