Okay, I have a nice idea for a book series that teaches children about history, but I'm not exactly sure which audience to focus on. From my understanding, YA books are for 5th to 8th graders. Children's books are obviously for younger kids. The problem is that I wanted to add a third-party character, if you will. A character that observes the historical events as they take place. So far, I have three idea for the third-party character. #1- The character in question is an immortal mice named Kevin (Or any other little creature). This does sound very cute, however I don't think that's proper for a YA story. (Reading "Ben and Me" about a mice and Ben Franklin is what inspired me to do this, so yeah...) I even thought of having him have a little mice family, but that might detract from the themes. #2- One (or two) modern-day kids travel back in time with a magical locket or some other thing. Haven't figured that part out yet. This could be better because these are not walking, talking animals and they're the same age. #3- The third-party character differs from book to book. It's a boy/girl from the time period that ranges anywhere from 10 to 14 years of age. Another problem is that, well, say the first book was about Thomas Edison. I want to show his determination and vigor without going overboard and not making any sense for the children reading it. How would I make them care about Edison? How could I make them relate to a guy that's been dead for well over a hundred years? Tips?