You're doing a lot better than you think. When my wife and I broke up, she put the kids back in school and every last one was #1 in their class. Trying to teach kids information like "What year was the Battle of Concord Bridge?" is Ok, but teaching them how to find out what they need to know, is something that will stay with them forever.

I never lectured, except a little in math. What I did was to give out reading assignments where the kids had to look something up, read it and then write a paper on it. Then we'd go over what they wrote correcting for grammar and spelling as we went. By the time my boys were 12-14 they were reading Plato and Aristotle. Just guide your son toward what you want him to learn and teach him how to think about it. I'm always here if you need me!