One problem with the label "learning disabilities" encompasses a huge number of related and unrelated learning patterns, social and psychological problems, and in some of the research I found, also physical problems like visual and hearing loss.
The easiest "types" of learning differences to describe are: dysgraphia "difficulty writing," and dyslexia, "difficulty reading."
Dyslexia, generally, is a disorder that affects the student's ability to make sense of printed material (note that this includes the notes you write on the overhead and chalkboard!). Most of us think of backward letters when we think of dyslexia, but that one of the manifestations of more serious problems than switching "d" and "b." These reversals also work at the sentence level: "to go the store" for "go to the store," and at the conceptual level: the student might start with the "middle" part of what she wanted to say, then end a sentence with an unfinished sentence, the "start" of the concept she intended.