Strong shapes
Design & Technology · Early Years · The School
The triangle
Push the corner of a paper square. It flops into a diamond. Now push a triangle. It holds firm. Its sides cannot change length. So its angles cannot change either. That is why you see triangles in bridges. And in roofs. And in cranes and pylons. Look up and you will find them.
Making a square rigid
Add one strip across a floppy square, corner to corner. Now it is two triangles. It stops flopping straight away. That strip is called a BRACE. Adding one is often the whole fix for a wobbly model.
Tubes and folds
Roll a sheet of paper into a tube. Stand it up. It will hold real weight. The flat sheet holds none at all. Now fold some paper into a zigzag. It gets stiff in the same way. The shape is doing the work here, not the stuff it is made of. You have not added any thickness.
Put two mugs on a table with a gap between them. Lay a flat sheet of A4 across the gap. Put a book on it. It collapses. Now roll the SAME sheet into a tight tube. Stand it up. Rest the book on top. It holds. Now fold another sheet into a zigzag. Lay that across the gap. It holds a book too. The paper was the same every time. The shape did the work.