1 - Getting Started ~5 mins
I'm holding a loose square made of card strips. If I push one corner sideways, what do you think will happen?
Hands up your guess: will it stay square, or will it lean over?
2 - What Holds Its Shape? ~8 mins
Which shape do you think will refuse to lean: a square or a triangle?
Two words for today. Rigid means a shape keeps its form when you push it. A brace is an extra strip that stops a frame leaning.
We will build both shapes the same way, keep the pins wobbly, and push one corner sideways with one finger. Then we will try one brace on the square.
3 - Build and Push the Frames ~22 mins
In your group, join four equal card strips into a square with split pins, and three strips into a triangle the same way. Keep the pins wobbly so the corners can move.
Hold each frame flat on the desk. Push one corner sideways. What happens?
Then pin one extra strip across the square, corner to corner. Push again. What changed?
4 - Record the Results ~10 mins
On your Investigation Journal page, record what happened to each shape.
For the square, the triangle, and the braced square, note: did it move, and what the extra strip changed.
5 - Triangle Hunt ~10 mins
A structure is something built to hold its shape and do a job, like a gate, a roof or a bike.
Look at the photograph cards and think about places around our school. Where can you spot triangles that are doing a real job holding something up?
Sort each find into the three job groups on the board: Roof or frame · Gate or fence · Machine.
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