this might be helpful:

Dear Word Detective: A colleague has asked me if I can tell him the origin of "crib" (in the sense of a prepared set of answers). I cannot find anything on the etymology of this word, although I suspect it comes from "scribere." Can you help? -- Jon Bradshaw, via the internet.

"Prepared set of answers"? Say, do you happen to work in the public relations industry, perhaps as a government spokesperson? You certainly have the requisite gift of golden euphemism. Back where I come from, "cribs" were also known as "cheat sheets," and possession of one during a school exam was grounds for expulsion. More tolerated were the "ponies," or literal translations (which "carried" us), that we sometimes used in class to practice translating classical works from Latin.

Speaking as a former Latin student, however, I think you deserve at least ten extra points for your excellent guess that "crib" in this sense comes from the Latin "scribere," meaning "to write." It's such a logical suggestion that it ought to be true, and it's a darn shame that it isn't. The first question that occurs to most people when they encounter the use of "crib" to mean "cheater's aid" is whether this usage can possibly be related to the sort of "crib," or small enclosed bed, in which infants sleep so innocently. Surprisingly, the answer is yes. When "crib" entered Old English from the Old High German "krippa" sometime before A.D. 1000, it originally meant "manger," the trough or stall where animals are fed. Over the subsequent centuries, "crib" acquired all sorts of other meanings, including "small cabin," "narrow room," "basket," and, of course, "child's bed" around 1649.
It was the "basket" sense of "crib" that apparently gave rise in the 18th century to the use of "crib" as a verb meaning "to steal." The exact logic of this transference is unclear, but it may stem from thieves' use of baskets or bags to conceal the articles they filched from stalls and shops. In any case, by 1778, "crib" had also come to mean "to plagiarize," or steal someone else's written work, and by 1827 "crib" was being used to mean "a translation surreptitiously used by a student to cheat." Today, of course, "crib" is used more broadly to mean anything containing answers that one ought to know without such an aid.