Someone in the comments brought to my attention the fact that the whole no-prepositions-at-the-end-of-a-sentence thing is not actually a rule anymore.
I missed that somewhere along the line.
The website that commenter Lee Seitz provided was the work of Grammar Girl: http://www.quickanddirtytips.com/education/grammar/ending-a-sentence-with-a-preposition?page=2.
The basic summary is that people were traditionally taught not to end sentences with prepositions, but nowadays most grammarians say it's okay. Why? For the same reason I usually ignore the rule: Nobody talks that way.
Astounded, I went to my bookshelf to research this rule a bit and see if everyone is in agreement on this.
My go-to guide for writing and grammar things is Strunk and White's The Elements of Style (4th ed.), and they have this to say on the matter:
Years ago, students were warned not to end a sentence with a preposition;
time, of course, has softened that rigid decree. Not only is the preposition
acceptable at the end, sometimes it is more effective in that spot than
anywhere else. "A claw hammer, not an ax, was the tool he murdered
her with." This is preferable to "A claw hammer, not an ax, was the
tool with which he murdered her." Why? Because it sounds more
violent, more like murder. A matter of ear. (77-78)
So I'm not insane- the preposition rule was once a thing. But do people still consider it a thing? Which people? What would my professors say?
I went to the writing handbook that my university uses as a textbook in the 100 level English classes to see if the preposition rule is still a thing here. It's the University of Alabama's version of A Writer's Reference (7th ed.) with Writing in the Disciplines. We fondly refer to it as the Hacker Handbook, since it's written by Diana Hacker and Nancy Sommers.
As a fun side note, I never actually bought this book because I didn't take EN 101 here (AP credit- it's cool!). I was actually visiting one of my professors about a paper and he just gave me his older copy when I told him I didn't have one. Pretty cool. He's an awesome guy.
I looked at the sections about prepositions in the Hacker Handbook, and neither section said anything about the placement of prepositions at the end of a sentence. I guess it's really, really not a thing anymore.
Although I'm personally still going to stick to the rule in academic writing whenever it's reasonable to do so, because while the rule may be what Grammar Girl calls a "myth," it's a very widely believed one, and I don't want to lose points on a paper for something as dumb as prepositions.
But let's get one thing straight, people: It is still very, very, veeeery wrong to end your sentence with the word "at" in cases like the ones I discussed in my previous rant. In fact, it's also usually wrong to end your sentence with the word "to" for the very same reason. It doesn't belong in the sentence. It has no purpose. It's unnecessary. You don't need it. You're wasting your breath and printer ink.
So end your sentence with "from," "on," and "with" all you want-
Kick "at" to the curb.
(And his equally useless friend "to.")