التقوية والتصليب والتدعيم
Design & Technology · Key Stage 2 · The School
Three different jobs
They sound alike and are not. STRENGTHENING makes something able to carry more before it breaks. STIFFENING makes it bend less under the same load. REINFORCING adds material at the one place that fails first. A shelf that sags is not weak — it is not stiff, and adding a strip along its front edge fixes it without adding strength anywhere else.
Why triangles
Push a square frame sideways and it folds into a diamond, because its corners can change angle. A triangle cannot change shape without one of its sides changing length, which is far harder. That is why bridges, roofs, pylons and bike frames are full of triangles, and why one diagonal brace across a square frame stops it folding.
Shape does more than material
You can stiffen paper enormously without making it stronger, by folding it: a flat sheet collapses, the same sheet folded into a corrugation carries a book. Tubes resist bending better than solid rods of the same weight. Choosing the shape is usually cheaper and lighter than choosing a heavier material — the cutting and gluing itself belongs in a workshop with an adult, not from a screen.
A card shelf sags in the middle under a book, but nothing snaps. Is it weak? No — it did not break, so it is not STRONG that is missing, it is STIFF. The fix is a folded lip along the front edge, which resists bending. Now a card bracket snaps clean off at the corner: that IS a strength problem, and the fix is REINFORCING — extra material at that corner. Different words, different fixes.