Coding classes in North Lanarkshire

The learner starts with thirteen standard web colours, each stored as three numbers from 0 to 255 for red, green and blue. Treating those as a point in a cube, the obvious measure of difference is the straight-line distance between two points. Then the learner converts each colour into CIELAB, a colour space designed so that equal distances look roughly equally different to a human eye, and measures again. The colours are standard ones chosen for the exercise, not the factory's actual paints.

RGB distance says grey is exactly as far from teal as from olive, 128 either way. CIELAB says teal is only about half as distinct as olive, which the learner can judge by putting the two pairs side by side. Yellow and lime sit as far apart in RGB as lime and cyan, yet look much more alike. The reason is that the eye is far more sensitive to some changes than others, while RGB treats every step of every channel as equal.

Next the learner picks five colours for five factory units, trying to make the closest pair as different as possible. A greedy method, adding at each step whichever colour is furthest from those already chosen, reaches a smallest CIELAB difference of 74.2. Checking all 1,287 possible five-colour sets finds a better answer, red, blue, lime, cyan and olive, at 85.8: greedy is fast, not guaranteed. Finally, labels must be readable. The WCAG contrast ratio, used by web designers, gives white text on yellow just 1.07 to 1, almost invisible, against 19.56 to 1 for black on yellow. White on red scores 4.00, below the 4.5 usually recommended for normal text.

Measuring whether a design really works for the people using it is the reason a North Lanarkshire teenager should still learn to code in 2026. The longer argument is in why teenagers should still learn to code in 2026.