This is a picture book format biography of Eratosthenes, who lived in Ancient Greece, focusing on how he calculated the size of the Earth using a mathematical formula and measurements taken by measuring shadows and length of footsteps from one location to another. Eratostehenes had many roles and talents, one being that he was a mathematician and author of books on several topics. He wrote the first geography book, which included the first map of the world and the first documentation of the size of the Earth.
The publisher says this is for ages 4-8 however the math concept of the formula he used to determine the size of the Earth was too complex for my 6 year old to grasp. The text is long-ish compared to a typical picture book as well, so I think this can extend a little beyond 8 yrs. if it is acting as a brief biography. I am not sure how many chapter book format biographies are out there for kids 9 and up on Eratosthenes, so this may be better than nothing for older kids!
The colorful pictures are nice and really compliment the text, especially when showing how he thought about measuring the Earth and comparing it to a grapefruit. It also addresses the idea of asking questions, curiosity, and making guesses at answers about things in the world that they did not yet know about.
This is a combination of history, math, and geography with a little scientific thought thrown in. It laid out his first questions and theories and how he came up with different ideas to come up with a way to measure a part of the land. We learn about what worked and what failed, leading up to how he finally came to a method that he thought was accurate, and why he thought this formula would work. His computation was about 200 miles off of the distance we measured in this century!
Within the story we learn about what schools were like for boys in Ancient Greece, that books were in scroll format, what libraries were like (and that they were rare) and other tidbits.
There is a bibliography included that can be used for further reading resources as well. This book is also a great example of how one book can cross over several subject areas: math, history, science and geography.