Coding classes in Cornwall

The ITU's Morse recommendation sets the timing precisely: a dot is one unit, and "A dash is equal to three dots"; the gap inside a letter is one unit, between letters three, between words seven. The learner first writes an encoder and uses those rules to time every letter. E, a single dot, lasts one unit. J, Q and Y each last thirteen. S lasts five units with only three units of key-down time, while O, three dashes, lasts eleven with nine units of key-down. That difference is exactly the wear on Poldhu's switches that the Marconi Centre describes.

Morse is not a prefix-free code: the code for E is the start of the code for S, and S is the start of H. So when the three-unit gaps between letters disappear, a stream of dots and dashes can be carved up in many different ways, each giving valid letters. The learner writes a recursive function that tries every way to take the first letter and then counts the readings of what is left. For CORNWALL there are 6,138,768 of them. The gaps are not decoration. They are the information that makes Morse readable at all.

The last column is the programming lesson. The plain recursive count for CORNWALL makes 12,759,484 function calls, because it keeps re-solving the same tail of the message. Add a memory, so that each tail's answer is stored the first time and simply looked up after that, and the program meets only 26 distinct subproblems, one for each position in the 25-element signal plus the empty end. Same answer, a tiny fraction of the work. That trick, memoisation, turns up everywhere from spell checkers to route planners.

So a Cornwall teenager should learn to code in 2026 to recognise when an answer only looks certain, a lesson that goes back to three dots heard off Newfoundland. The longer argument is in why teenagers should still learn to code in 2026.