Session 1 · DESIGN: Discover
Squash, stretch, twist
- 10 minHook: hold up a paper sheet between two cups and put a coin on it. It collapses. Fold it into a zigzag and try again. What changed?
- 20 minStructure walk: photograph five structures around the school. Mark on each where it is squashed (compression) and where it is stretched (tension).
- 15 minForce hunt with a kitchen sponge: draw lines on it, then squash, stretch, bend and twist it. Sketch what happens to the lines.
- 5 minChoose your context: flying fox, earthquake tower or cyclone fale. Write one question you want answered.
Session 2 · DESIGN: Explore
Why triangles win
- 10 minTechnical words: horizontal, vertical, diagonal, span, rigid, brace. Draw a double-ended arrow on a sketch for each.
- 20 minBuild a square and a triangle from straws and pins. Push each corner. Add one diagonal to the square and test again.
- 15 minLook at photos of Auckland Harbour Bridge and Makatote Viaduct. Count the triangles. Where are the diagonal braces?
- 5 minExit card: explain in one sentence why a triangle keeps its shape.
Getting started
Start with the sponge test and name just two forces: squash and stretch.
Stretch
Find an example of shear and torsion at school, and explain how the structure resists them.
Checkpoint
Five photos labelled with tension and compression, and a braced square that no longer wobbles.
Activities for this week
- Sponge force hunt: What do squashing, stretching, bending and twisting look like inside a material?
- Square or triangle?: Why do engineers fill bridges, towers and cranes with triangles?
Useful this week
- Halting the jolts: how Te Papa resists earthquakes ↗ See how a New Zealand invention lets a whole museum slide gently in an earthquake.
- Auckland Harbour Bridge opens ↗ The story of our best-known truss bridge and why it needed extra lanes.
- Bridges and tunnels ↗ Photos and stories of how Aotearoa crossed rivers and gorges.
- Physical World: forces ↗ Clear explanations and activities about forces and motion.