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Design & Technology · Key Stage 1 · The School
Why things fall over
A structure is STABLE when its weight acts over its base. A wide base and a low CENTRE OF GRAVITY make it hard to topple; tall and narrow makes it easy. That is why a road cone is the shape it is, and why a tall model always needs a wider foot than it looks like it needs.
Three ways to strengthen
BRACING — add triangles. LAMINATING — glue layers together so they act as one thick piece. FOLDING or TUBING — change the cross-section so the shape resists bending. Each adds strength without much weight, which is the whole game.
A fair test
Add weight in equal steps and record when it fails. Change only ONE thing between designs — if you alter the material and the shape at the same time, you cannot say which mattered. That single rule is the difference between testing and just trying things.
A straw tower wobbles. FIX 1, wider base: splay the bottom straws outwards — better. FIX 2, triangulation: tape a diagonal straw across each square face, turning it into two triangles — much better, because a triangle cannot change shape without something breaking. FIX 3, lower the weight: move the heavy part to the bottom. Try each on its own and rank them; triangulation usually wins.