I see it like writing a paper. Mechanically, the stuff required of a paper might be there. Page numbers, citations, et cetra (hee!). But if the content is crap, I'm going to fail.

I wouldn't use text speak while filling out forms, but I will use abbreviations like "N/A."

::muses on these distinctions::

Now I'm wondering when it stops/starts being either abbreviation and/or textspeak. IDK, to me, is not an abbreviation because I've only encountered it in texting.

Well, per Wordnik, it's new. [link] Unlike OK, which has been widely used all of my life. [link]

Oooh! I am loving Wordnik!!

Wordnik is the bizzomb. And Buffista-founded!

Which makes it all the better.

I find flunking a test based on one answer problematic. But I also wouldn't use FYI or OK on a test. Even in the dark days before texting, I told my students that we were using formal academic English on everything except their journals, and that they'd be graded accordingly. Would I have dismissed the rest of the test because of one IDK? Not at the beginning of the semester. At the end, hell yeah. Of course, if they didn't know better by that point they probably wouldn't have learned much else, either, so odds are I wouldn't have been trashing an otherwise perfect work.

In Sis' case, she went extreme at the beginning because for two years she has tried subtle and if there is one that she has learned about her students, it's that they don't get subtle. Big screaming fail, however, they get. Now, it's out there, everyone knows it, and from here on out they have no excuse not to use spelled out English words on short answers.