Structures that stand up
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 makes it hard to topple. So does a low CENTRE OF GRAVITY. Tall and narrow makes it easy to topple. That is why a road cone is the shape it is. And it is why a tall model always needs a wider foot than it looks like it needs.
Three ways to strengthen
There are three ways to strengthen a structure. 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 one adds strength without much weight. That is the whole game.
A fair test
Add weight in equal steps. Record when it fails. Change only ONE thing between designs. Alter the material and the shape at the same time and you cannot say which one mattered. That single rule is the difference between testing and just trying things.
A straw tower wobbles. FIX 1 is a wider base. Splay the bottom straws outwards. That is better. FIX 2 is triangulation. Tape a diagonal straw across each square face. Now it is two triangles. That is much better, because a triangle cannot change shape unless something breaks. FIX 3 is lowering the weight. Move the heavy part to the bottom. Try each fix on its own, then rank them. Triangulation usually wins.