The 34th Magic Tree House Fact Tracker, Dogsledding and Extreme Sports by Mary Pope Osborne and Natalie Pope Boyce (Lexile: 820; Interest Level: Grades 3-5) is the nonfiction companion book to Balto of the Blue Dawn by Mary Pope Osborne. You do not have to read the fiction story to understand the nonfiction in this book.
Most of the information in this book tells about dogsledding and the Iditarod race, including both some history and some modern stories, including some from 2015! Some more information is provided about other extreme sports (snowboarding, skateboarding, free climbing) and the people who participate in these sports.
I found that this book was quite interesting, and the information was well-presented. I was especially impressed with the "how to do more research" section at the end of the book. This is a strong nonfiction book, especially if you are looking for information about people who participate in extreme sports. (128 p.)
One of the reasons I became an elementary school librarian is so I can read children's books.