The Happiest Tree: A Story of Growing Up by Hyeon-Ju Lee has a mature theme. The ideas of how sweet and harsh life is might be above the traditional picture book crowd. As is the fact Lee is speaking of how there is happiness, sorrow and pain in life as we grow.
The idea is simple at first look: the tree is growing and is a voyeur looking at the people on each floor. Time is shown to pass by the fact the tree (the narrator of their own story) tells you “When I was 10, 20, etc.) and you can see that the tree has more leaves, wider branches and relative to other markers, has gone pass them. In a deeper manner, it is talking about the emotions one feels (joy listening to music, happiness of watching puppies being born, the sadness of watching a grandmother in a darken room look at family pictures). It is also about death. As on the first two floors you see children and the puppies, but farther up you see the grandmother.
Lee’s illustrations are slightly abstract art with realism touches as well. Overall, this book is there to work on your emotions. Of course, reading the text is solid, but everyone should feel a mixture of happiness, sadness and even calm. The illustrations reflect what the text is saying by having sun on good moments and heavy, large drop rain when there is a sad moment.
If I was a teacher, I would use this book to talk about writing in a junior high, high school or even college course. And it would be an interesting book to use if you are looking for a grief book without having death be obvious.