Probably Dan and John are both getting close to the mark here (and even
Dewey's ghost-like presence in John's post!).
Maybe we can imagine communication as in a comms channel with a source and
a receiver. The source must be clear, to be sure. Poorly formulated
ideas may be transmitted and received (and processed) perfectly well - and
be wrong.
The channel is probably some combination of careful listening and
familiarity with the encoding scheme. That is, the signal should not be
distorted by sloppy transmission (which, in my model, has more to do with
the student, though some teachers can make this unbearable) or by misusing
or misunderstanding the jargon that is used (we have had plenty of
discussion on this list about that).
Finally, and most importantly, correct reception requires processing of
the signal as it arrives. In the teaching / learning context, I'd call
this _engagement_ with the material / concepts / ideas / themes, so that
the learner actively recreates his or her personal ownership of these
things - I just felt a rush of cold air and a far-off voice wailing
"constructivism" in the room ;-)