like the words he heard around him were the ones that had both colors in them, and that these were very often in the form of consonant- color + vowel-color + consonant-color. If he ever asked, "What do you call this kind of letter, and what do you call this kind?" (I can't guess whether a child would be likely to do this), I would say, "We call these kinds of letters 'vowels' and these consonants."' (If he asked why, I would tell him I didn't know.)
