I often haul out the dictionary. It seems to sum up some of these big concepts in broad enough terms that I don't feel like he'll be limited by my perspective on stuff (and lack of knowledge).
I did this for 'parallel' the other night. Really, I should know that one, but my explanation was just not getting it done. And from the teacher ds had gleaned that parallel meant 'the same'. (??)
We found in the dictionary the other part of the sentence: moving in the same direction and never getting any closer. This really clicked for him. Whew.
(again wondering about the 'hearing' but that is another topic...)
