Online coding and Python classes in Warrington

The learner writes a Python pattern that finds each "Born ... Died ..." line in Walker's book and pulls out the two years. One record, Joseph Black's, has a footnote marker straight after the year and slips past the first version, which is itself a lesson: 53 found, 54 expected. Once all 54 are in, the program applies data validation rules, simple tests every sensible record should pass. The first rule follows the title: everyone should have been alive in 1807 or 1808.

Three people fail the 1807 rule: Joseph Black, Henry Cort and Priestley, spelled Priestly in the book. A careless program would delete them. But the preface explains that an appendix was added for Black, Cort, Ivory and Priestly, who could not be included in the engraving the book was written to accompany. The flags are real, and the records are fine. The second rule, age at death under 40, flags only Priestley, at 31. That one is a genuine error, and a second source proves it.

Priestley's own memoir says he was born "on the thirteenth of March, old style 1733". Britain switched from the Old Style calendar to the new one in 1752, which moved dates on by 11 days, so 13 March Old Style is 24 March in the new reckoning. Walker had the day exactly right and the year wrong: 1773 for 1733. The learner writes both findings into the report, fixes only the proven error, and notes that the median age at death did not move at all, while the mean did.

Looking for a second source before believing a date is the kind of habit that makes code worth learning for Warrington teenagers in 2026. The longer argument is in why teenagers should still learn to code in 2026.