Coding classes in Surrey

GPS satellites do not broadcast a date. They broadcast a week number counted from a Sunday in January 1980, and in the legacy civil message that number is carried in ten bits. Ten bits hold 0 to 1,023. On the 1,024th week the field has nowhere to go, so it reads zero again, and a receiver that takes the number at face value decides it is 1980. The learner's job is to work out exactly when that happens, three times over, and then check their answer against the organisation that runs the system.

Two details make this a real lesson rather than a trick. The first is that odd 23:59:42. GPS time ignores leap seconds and UTC does not, so GPS is now eighteen seconds ahead; midnight at the start of a GPS week therefore falls eighteen seconds before midnight UTC. A learner who does not know that gets every answer eighteen seconds late and cannot tell whether their code or their understanding is wrong. The second is that the check is against a published fact. We did not look up the dates and write them down. We computed them, and only then compared, which is the only version of this exercise that teaches anything.

Modern Age Coders has no connection with Surrey Satellite Technology, Airbus, the University of Surrey, Surrey County Council or the United States government, and nothing here implies one. The addresses and founding dates are theirs; the arithmetic, and any error in it, is ours.

So the case for a Surrey child learning to code in 2026 is not that the machine cannot write the code. It is that somebody has to know what to ask it, and to recognise a confident wrong answer when it arrives. The longer argument is in why teenagers should still learn to code in 2026.