Coding classes in Rhondda Cynon Taf

First the holes. A circle's area is pi times the diameter squared, over four, and the learner codes it for the three sizes in the record. The diameters go 3, 2, 1, but the areas go 9, 4, 1, so the largest hole does almost two thirds of the work. Each metre of bridge width loses nearly 9 cubic metres of stone to one set of three holes, which at a typical 2,400 kilograms per cubic metre, our assumption, is about 21 tonnes. That weight was sitting where Edwards least wanted it.

Now the harder idea. Take a stone arch and build a copy exactly twice as big in every direction. Its weight depends on volume, so it grows eight times. The stone that carries that weight works through cross-sections, which grow only four times. Every square centimetre of the bigger arch therefore bears twice the load. The learner codes this square-cube law for arches scaled from an invented 10 metre model: at 20 metres the stress doubles, at 30 metres it triples, and at Pontypridd's 42.7 metres the arch is about 78 times heavier than the model while the stone bears over four times the stress. Galileo made the same argument about beams and bones in 1638.

There is a classic slip to catch. Use the diameter where the radius belongs, and the program claims one set of holes removes 35.6 square metres per face, four times the truth. Learners add a test: a hole can never be larger than the square that just contains it. We should also be honest about the model. The record says Edwards pierced the stone to relieve pressure on the arch; the full story involves where the weight sits and how it pushes the arch out of shape, which our sums do not attempt.

Knowing that not everything scales the same way is a strong reason for a Rhondda Cynon Taf teenager to stay with coding in 2026. The longer argument is in why teenagers should still learn to code in 2026.