For whatever reason, I never got H. into the habit of reading to me. Maybe it's just because it was too boring to me, or maybe if we were going to spend time looking at a book together, it was more rewarding for me to read to him, with intonation that helps convey meaning and more control on where we pause so that I can explain things. Oh I remember now: when he was solidifying his reading skills, particularly when he was 3-4, I wanted to switch back and forth reading with him, but he resisted this a lot, and I didn't want to force him, so we didn't do that very much. Later on, I started falling asleep when reading to him, and he would then pick up the book and keep reading out loud, which gave me an excellent nap.
Ever since H. was a baby, I have been in the habit of pausing to explain virtually every word I read to him. When he was younger (like 3-4) he would look expectantly at me if I read an unfamiliar word that I didn't explain. He doesn't do that anymore, but occasionally I'll forget to define some word and he'll just ask me what it means. So, yes, he does ask, but not very often, partly because I automatically define them for him, partly because he doesn't mind not knowing, apparently!
I don't know where he'd be testing on vocabulary, but I can tell you that he can now (at age 6) read
Treasure Island without looking up words, and he can still more or less understand and enjoy it, but he still doesn't understand several words per page. (For comparison, I distinctly remember my mother reading
Treasure Island to me when I was in 4th or 5th grade, and it while I more less understood it, there were many words I didn't know.) Just 20 minutes ago I started him reading it and he was complaining that he didn't want to look up words he doesn't know, but I insist that he do so, for vocabulary practice.
Between the ages of 2.5 and 4.5 or so we completely read through the Oxford Picture Dictionary. I'm sure that did some good. We've also read three of the "Vocabulary Power" books, like this:
http://www.amazon.com/Vocabulary-Power-Grade-Audrey-Carangelo/dp/1602140049/ref=sr_1_1 We've read vocabulary from other sources as well, such as my PowerPoint presentations which introduce quite a bit of vocabulary.
Completely off-topic, I recently bought this grammar video series for H.:
http://www.splashesfromtheriver.com/grammar_course.htm I love this lady, and H. liked the sample videos too. I am sure a lot of others here will appreciate certain production features, although it is slow-paced. Well, as a child gets older, I think difficult/abstract information needs to be presented more slowly. It requires mulling. Her explanations are
extremely clear and simple, in the sense of being easy to grasp, not in the sense of being oversimplifications.