No doubt you know that most venerable of usage crotchets, the mistaken English-must-resemble-Latin zombie rule that prohibits prepositions at the end of sentences.
Almost equally venerable is the denunciation. In the first edition of A Dictionary of Modern English Usage in 1926, H.W. Fowler published an entry on the "cherished superstition that prepositions must, in spite of the incurable English instinct for putting them late ... be kept true to their name & placed before the word they govern."*
Laying the blame at John Dryden's door, Fowler observes that "even now immense pains are daily expended in changing spontaneous into artificial English."
But now one of my spies informs me of a member of a university faculty for whom mere long-exposed superstition will not suffice, but must be extended into absolute nonsense. He, or she, commented on a student's paper, "Do not begin or end a sentence with a preposition."
The student had the temerity to challenge this, with a link to an Oxford Dictionaries post on superstitions, and received this reply:
Look up Strunk and White (1918) for good rules on writing. Also, I recommend you do not use prepositions at the beginning or end of sentences their use does not reflect well on the writers.
I do not agree with you on your point and from now on I will mark you down if you use prepositions to begin or end ssentences as you have now been advised to do so. Once you get out of my class use them anywhere you would like.
Other people like Winston Churchill had the same thought as you when his editors made the same correction. Churchill said, "Ending a sentence with a preposition is something up with which I will not put." So you have good company of those who disagree with using proper grammar -- or at least this rule in grammar.
Where, in this rich trove, to begin?
First, as is common among the peeververein, evidence to the contrary, the Oxford Dictionaries link, is merely ignored.
We have instead a citation of a nonexistent text. "Strunk and White" is E.B. White's expansion in 1959 of William Strunk Jr.'s 1918 style guide for Cornell students.
Then, when we trouble to look up Strunk's 1918 text at Bartleby.com, we discover that the section on "Elementary Rules of Usage" makes no mention of prepositions at either end of the sentence.
Rounding it out, the professor will exercise petty tyranny to penalize the student for violation of this doubly bogus rule, and, one must inevitably think, for the temerity of challenging him.
Now the student must defer to barefaced ignorance to get a passing grade, an experience that I think most of us have endured in our academic careers.
Luckily, the professor is presented anonymously by my informant. Otherwise, I'd suggest, after Congreve's Lady Wishfort, having him bastinadoed with broomsticks.
*You'll note how neatly the Etymological Fallacy dovetails with the superstition. Since the roots of preposition are "place before," that must settle the matter, right?