So what's the scoop (or is it the shoop)?
The word came into English legal and official language from French in the 1300s, at which time it was written "sedule" or "cedule" (plus other variants) and meant "a slip of paper containing writing". The first syllable was pronounced the only way it could be pronounced: "SED". In modern French cédule is still pronounced this way, and most European languages other than English followed suit:
Provençal cedula, cedola
Why did we English speakers mess things up? French had acquired this word, like most of its vocabulary, from Latin, and this was the root of the problem. In Latin, the word was scedula (in medieval and modern Latin also written schedula), a diminutive of Latin sceda (medieval Latin also scheda), a page or a strip of papyrus. This was probably a back-formation from schedium (an impromptu speech) in turn derived from Greek schedios (casual);. In Latin, the first syllable was pronounced SKAYD. But in the passage from Latin to French, the "K" sound had fallen out of the word.
As regular Wordlady readers know, Latin messed up our spelling big time the 16th century. Scholars of the time looked at the original Latin and Greek words from which many English words were ultimately derived and said "Hey! We should spell our English words like that too [so that people will know I'm really smart and know Latin]!". So, sensible old "sedule" had to be changed to "scedule" or the even more popular "schedule". People still pronounced it "sedule", though (much as we still pronounce "debt" as "det" despite that interloping Latin "b"), until well into the 19th century.
This is the point at which the SHED/SKED schism (SHIZZM? SIZZM? SKIZZM?) took place. Noah Webster convinced his American compatriots that the pronunciation should reflect the Greek origin of the word, and follow the example of similarly Greek-derived "school" and "scheme". In Britain, however, the SED pronunciation morphed into a SHED.
We Canadians? Of COURSE we have to have both pronunciations. When we surveyed people for the Canadian Oxford Dictionary on this question, we found that more Canadians said "SKED" than "SHED", but that both pronunciations exist. The "SHED" crew tend to think that the "SKED" lot are traitors to Canadian nationality, having adopted an American pronunciation. This is quite a ridiculous attitude to take, as we don't feel the same way about the vast majority of Canadians who say "toMAYto" like Americans rather than "toMAHto" like the British. I say "SHED", by the way, but am unperturbed by those who say "SKED".
The now most common meaning of "schedule", a timetable, is a fairly recent development, dating only from the mid-19th century in the US. From being an official piece of paper in the Middle Ages, "schedule" came to apply to tabular listings of figures (which is why we have "schedules" to attach to our income tax returns). With the coming of the railways, it was a handy word to use for tabular timetables.
Another thing that happened to "schedule" in the 19th century as a result of the railways was that it started to be used (here comes my hobbyhorse) as ... gasp... a verb. Noun-verb conversions, what would we do without them? Indeed, having now finished writing this, I am moving my cursor over to ... schedule it for publication.
P.S. If you find the English language fascinating, you might enjoy regular updates about English usage and word origins from Wordlady. Receive every new post delivered right to your inbox! You can either:
use the subscribe window at the top of this page
(if you are reading this on a mobile device): send me an email with the subject line SUBSCRIBE at email@example.com
Follow me on twitter: @thewordlady