Coding classes in Conwy county borough

All the sizes in the model are invented. The learner takes a fixed amount of iron, a cross-section of about 0.48 square metres, and arranges it three ways: as a solid square bar, as a wide flat plate, and as a hollow box 4.5 metres wide and 7.5 metres deep with walls 20 millimetres thick. How much a beam resists bending depends on a quantity called the second moment of area, which grows with the cube of the depth, because metal far from the middle does most of the work. The program computes it for each shape.

The hollow box wins overwhelmingly: the same iron bends 205 times less than as a solid bar and thousands of times less than as a flat plate, simply because it is spread out as far from the centre as possible. Next the learner lets a beam sag under an even load. The textbook formula says the sag grows with the fourth power of the span, so doubling the span from 60 to 120 metres multiplies the sag by exactly 16, from 1.4 centimetres to about 22 centimetres in the model.

Then the extra pier. With a support added in the middle of a 120 metre beam, the program combines two known solutions, the sag under the even load and the upward push of the new support, and checks that the beam sits exactly on the support. The largest sag falls from about 22 centimetres to under 6 millimetres, roughly 38 times less, and moves to a point about 25 metres from each end. The record does not say why piers were added in 1899, and the model does not claim to know; it shows why an extra support is such a powerful fix.

Checking how a quantity really scales before trusting it: that is a reason for Conwy teenagers to keep coding in 2026. The longer argument is in why teenagers should still learn to code in 2026.