Not actually a rule, so much as a way of running an aspect of things -- which I suspect that many would, like me, regard as more than a bit daft.
This was a little over sixty years ago; came my way in the preparatory-school department of the minor public school which I attended. Would figure that this befell me, and reckonably others like me: particularly because of my having been a wimpy and sedentary kid -- hating, and having zero interest in, sport of any kind (then, and lifelong). "Then and there", participation in team sports was of course compulsory for all. The school's winter game was rugby; about which I, aged eleven, knew nothing beyond the fact that it existed. I can't have been the only new boy in this position; but nothing whatever was done officially, for any teacher to instruct those of us to whom this applied, in the rules and workings of rugby; we were just left to muddle through, or not. I -- loathing sport, and clueless not only about that area of life, but about most aspects of dealings with fellow-humans; continued to have no idea about what I, or others, were supposed to be up to rugby-wise.
My situation thus, came -- indirectly -- to the notice of the prep-school department's headmaster. This gentleman was a zealous and somewhat ferocious evangelical Christian (the school as a whole, was not a particularly religious outfit; this guy, as a Christian firebrand, was an individual outlier) -- he proceeded to berate me for my evil "pride" in not having taken steps to -- presumably by enquiring of fellow-pupils -- acquaint myself with the workings of rugby. (I've found that Christians of a certain stamp, can have assorted bizarre ideas about the forms in which "wicked pride" on the part of sinners, may take.) In my case, general lack of gumption -- and my being on the whole, unpopular along my schoolfellows -- led to my still not trying particularly, to consult "fellow-inmates" to get self genned-up about the game concerned; I continued to hover bewilderedly around on the rugby field.
Having in mind the way in which schools generally function: although my school was not one of the sharper knives in its section of the scholastic drawer; it seems difficult to conceive of not having teachers (normally hyper-eager to try to impart knowledge to often unwilling pupils) ready and on the spot to, officially, teach new kids about the workings of a sport hitherto basically unknown to them -- just through "absent-mindedness" as it were, on the school's part. One feels hence, that this omission must have been deliberate policy. And one wonders -- why? Maybe a legacy of "Christian craziness", more general in past times than circa 1960 when it was confined to our zealot headmaster; maybe -- with public schools being supposed to be for the forming of future leaders of the country's society -- intended to foster initiative on the part of pupils, rather than their being allowed to rely on being passively spoon-fed about everything; or who knows what other reason for this oddity of an establishment dedicated to teaching, deliberately refraining -- in this particular matter -- from teaching?
I'd be interested to hear whether any other participants here, had a similar experience at school -- whether re sport, or other supposedly necessary or highly salutary life skills -- or whether this was a particular random weirdness of what was, at any rate at the time of my attending it, in many ways a rather sad and shabby apology for a school.