...and sometimes it's not texting lingo or any form of dyslexia...it's a simple case of borderline illiteracy. I've see it often with the families of children I've worked with. It makes for a very uncomfortable situation when you get a parent note and your first thought is that the kid MUST have forged the note (except there's no reason why the kid would have). But you can't ask the parent about it because THAT would be awkward for both the parent and you.
My middle brother is quite intelligent, and reads a LOT, but he never gave a hoot about school, and he writes like he's in elementary school (and we're not talking 5th grade). I love him, but I cringe when I read his emails sometimes...