Hmm. At that age, with a similar child, we tried to expose him to a variety of topics and then fed whatever he seemed most interested in at the moment. So we might grab a variety of books (dinosaurs, cars, planets, dragons, etc.) from the library, and then he would let us know what interested him. We would then look for resources on that topic to share (games, puzzles, books, maps, etc.). I don't know if there is a best practice. Likely, someone has dreamt one up, but what worked for our family was simply to go where he wanted to go. Years later, he still remembers many of the facts and strings them together for comparison/contrast.
