Unfortunately, the thing about a structured education means that often, children are often thought to think in a certain way; while it might efficiently allow learning, it restricts their creativity. But moving back on topic.
Another reason why this series should not be considered a children's series? Death.
People die. All the time. Civilians, bystanders, innocent hork bajor, innocent kids, tons of yeerks. In every book, at least one person dies. In the first book? Elfangor dies. Ellimist? Sooo many deaths.