I've been a lurker for a couple of weeks here and actually purchased Bigger last year. After perusing it's pages though, I decided my newly-turned 8yo wasn't quite ready and sold it. I've taken another look at the samples and think it's perfect for him now. He'll soon be nine, but the interest level of the books is ideal and I look forward to teaching him at his level. In the past, I've watered it down from big brother's studies and have decided to try beefing it up for the older instead. I'm looking forward my younger being able to enjoy it for a change instead of watching his eyes glaze over with overwhelming information.
My question is if the older extension is enough for my 12yo? I own A Child's Story of America and he was ecstatic at the idea of reading it for history. We have been studying Creation to the Middle Ages for two years and he is eager to do some "more recent history studies". (His words in quotes.

I probably should mention that although the suggested ages match up nicely, I think Preparing is a bit too advanced for the 8yo and we will be finishing up our Middle Ages study just prior to beginning Bigger.
Your thoughts are appreciated,