The Librarian Who Measured the Earth

by Kathryn Lasky

A perfect introduction to mathematical concepts for young readers, written by a Newbery honor-winning author!

This colorfully illustrated biography of the Greek philosopher and scientist Eratosthenes, who compiled the first geography book and accurately measured the globe's circumference, is just right for budding mathematicians, scientists, historians, and librarians! Filled with fascinating details about Eratosthenes's world (and in print since 1994), kids are sure to flip through the pages time and again.

Genres: Picture Books, Biography, Mathematics, History, Science, Nonfiction, Childrens

48 pages, Hardcover

First published September 1, 1994

About the author

Kathryn Lasky, also known as Kathryn Lasky Knight and E. L. Swann, is an award-winning American author of over one hundred books for children and adults. Best known for the Guardians of Ga’Hoole series, her work has been translated into 19 languages and includes historical fiction, fantasy, and nonfiction.

Reviews

[Karen_educ250 · Rating 5 out of 5]

How I have used this book in the classroom...

My 5th graders loved this book. It's long for a read aloud in a math classroom (you usually don't want to spend half the class reading), but I found it was worth it. The students had to understand circumference and pi. After reading the book, we tried to determine the circumference of an orange using Archimedes' method. Next, they went on the playground and drew giant circles. I had the students make a table that labeled the circumference, diameter, and what the circumference divided by the diameter was for their circles. Eventually, someone noticed that no matter how big or small the circle, c/d was always close to the same. My students 'discovered' pi. Even better, I think they actually remembered it because of this book.

[Melki · Rating 4 out of 5]

Eratosthenes lived more than two thousand years ago. He was insatiably curious, and fascinated by many fields, but his main interest was in geography. He used math and measurement to estimate circumference of the earth. When our planet was remeasured this century, it was discovered that Eratosthenes' calculation was only off by 200 miles. Pretty amazing, huh?

This is a fascinating biography with beautiful illustrations by Kevin Hawkes.

[Karen Witzler · Rating 4 out of 5]

Eratosthenes and the Well at Syene.

[Chak · Rating 5 out of 5]

Great historical science book for ages 6 and above. It is a picture book, but covers a lot of information without being *too* text heavy on any one page. The story of Eratosthenes is interesting and his curiosity is very inspirational. My son was absolutely riveted by this book, but he is really into anything mathematical. If your child likes math concepts, this is a great narrative which features higher level math in an interesting and unintimidating way.

[Gary Anderson · Rating 4 out of 5]

This book has a lot of math, so math lovers out there, this one is for you! Eratosthenes was a Greek mathematician born roughly two thousand years ago. Kathryn Lasky’s picture book biography of Eratosthenes celebrates the intellectual qualities of curiosity, innovation, and persistence. The sun-soaked illustrations by Kevin Hawkes keep the mood on the light side even when the text veers toward the ponderous.

[Haley · Rating 4 out of 5]

We enjoyed this story that is part biography , part living book about math. It's incredible how he lived 2000 years ago and was able to use basic geometry, logic and math skills to figure out the circumference of the Earth with only a 200 mile degree of error. We don't give our minds enough credit and are so quick to just rely on a computer. This book was encouraging to see practical application of math skills!

[Nicole · Rating 5 out of 5]

What a great picture book to add to my collection and to introduce my students to life in Ancient Greece. The focus on asking questions throughout the book is great as well as the incredible details about daily life.

[Becky · Rating 4 out of 5]

Read for our geography/history study of Greece. This was one of those stories that I vaguely knew, but I learned quite a bit from this picture book biography myself. It really is incredible how accurately his method let him estimate the circumference of the earth. My kids were complaining about the length a bit, but that was probably because they were clamoring to finish up school by that point.

[David Freudenburg · Rating 3 out of 5]

Biography of Eratosthenes,3rd century BCE librarian at Alexandria who successfully and accurately calculated the circumference of the Earth! Oh, and, by the way, it was common scholarly knowledge at that time that the Earth was a sphere. Includes beautiful, large painted illustrations.

[Michelle Rogers · Rating 5 out of 5]

A wonderful picture book about the life of Eratosthenes, as well as how all areas of learning tie together to help us understand the world we live in. We really enjoyed this book!

[Jen · Rating 5 out of 5]

This was an INCREDIBLE book!!!!! My, but those Greeks were amazing! I read this book to my 4th grader and 8th grader and we were challenged by the mathematical concepts, but LOVED digging into it. Arcs and angles and distance and circumference all add up to a really exciting story of how a brilliant Greek man in the 3rd century BC was able to figure out how to measure the circumference of the Earth. Intriguing! Warning...be ready to dig into a few mathematical/geometry principles...if you have a line that intersects two parallel lines then opposite angles are equal! My kids were not content to turn the page until I could explain why Erastosthenes needed the sun to be shining straight down the well in one place in order to measure the angle of the sun in another and come up with an angle of 7.2 degrees. Very fascinating and well written book!

[Ciera · Rating 5 out of 5]

Most people think of math as 2+2 or 12 - 5...boring. But this book shows how math actually impacts the world and our lives. In ancient times with no computers, calculators, satellites (end of the world, right?!) Arasthenes managed to use mathematical calculations to measure the circumference of the earth...without even traveling all over the world! How'd he do it? That little thing that is a terror to little kids and yet has helped our world tremendously - math. Interested now? you better be...pick up that book and start reading!

[Ch_beverlyatwood · Rating 5 out of 5]

Erosthenes, born in ancient Greece was able to figure out the earth's circumference within 200 miles of the correct measurement by today's sophisticated measurement tools. What a feat, indeed! I had never heard of this brilliant Greek before. And the way he figured out the earth's circumference was amazing. I'm not a math person, but he certainly was. Students will enjoy this picture book because of the great pictures as well as the interesting facts about Erosthenes. I would use it when studying famous Greeks, inventors, mathematicians, geography and history. Highly recommended!

[Pumpkin+Bear · Rating 4 out of 5]

You can't get much closer to "living math" than when you read about real, live people who used math to do amazing things! Although this book is LONG for a read-aloud picture book, and is more suited to the older child who enjoys being read to (my eight-year-old was immersed in the story, but my six-year-old was a bit wriggly), it's a great living math book simply because Eratosthenes LOVED math for his entire life, and he loved learning, and the book makes those facts very evocative.

[Chessa · Rating 5 out of 5]

Great book! Cool illustrations and a well-told story of Eratosthenes, who since he was very little loved to ask questions and wonder about things. Great mathematical concepts woven in in the later third of the book - angles, circumference, geometry in general - but doesn't feel overly "teachy" at all - it's just a great story. In fact, it was so good that my kids were slightly disbelieving that it was true. ;)

Read to two kids, ages 9 and 5.

[Amy Rogers · Rating 4 out of 5]

Really good, and a cute story for all ages.

[MindfulMuslimReader · Rating 4 out of 5]

In contrast to the modern tendency to simply collect information, books like this highlight a lifetime spent in the pursuit of deep and varied knowledge - a very important part of our faith. Children can learn much from Eratosthenes’ journey starting with his insatiable appetite for knowledge as a child to his relocation as an adult to ancient Alexandria, where scholarship was central to society and deeply revered. Understanding how Eratosthenes was able to determine the circumference of the Earth leads to a deeper understanding of the Earth's orbit, the seasons, and the application of basic geometric principles. Enriching stories like this should be used as a means to cultivate a love of learning and build appreciation for the pursuit of knowledge. For a deeper look into the importance of teaching children the critical distinction between information vs. knowledge, read our blog post.

We rate children's books for virtue, language, story, and beauty and flag content advisories when needed.

Read more at MindfulMuslimReader.com.
“Books Worth Reading”

[Kathryn · Rating 5 out of 5]

This is really well done. I recommend it for upper-elementary as it's longer than most picture books and deals with mathematical concepts that will likely be beyond most of the younger picture book set. However, as a read-aloud even younger kids could glean much about the life and times of Eratosthenes even if the process of how he went about measuring the earth is a little more advanced. As someone who is not mathematically inclined, I admit that even I felt I needed something a bit further to help me really understand the details vs. just grasping the general concept -- I think I need something more visual like a video demonstrating the process vs. just the illustrations on page. That said, the illustrations are excellent and really help provide a sense of time and place and even include some humor and personality. Kathryn Lasky was a favorite author of mine when I was young and it was great to find this to share with my kids today. The subject really comes alive and I appreciate the Author's Note, Afterward and Bibliography. I'm wavering between four and five stars on this one, but I'm going to err on the side of generosity given my mathematical hang-ups ;-)

[Charlotte S · Rating 5 out of 5]

Long ago in ancient Greece, a baby was born, and his name was Eratosthenes. He was a curious child, always asking questions about the world. Through his youth, the question that enthralled him the most was how big the world was. He wanted to measure it! But he couldn't simply walk around it to find out. Could he stand in a spot and measure the Earth? Join him on his quest in this wonderful picture book biography!

This book is so amazing! I love the writing style - informative, yet engaging!
And the illustrations are so pretty! I love the facial expressions!
If you love science, math, or simply are a curious soul, then this book is perfect for you!

I hope you love this book as much as I do! Thank you for reading my review! Follow @bronteandwilder on Instagram for fun book recommendations!

[Jo Oehrlein · Rating 3 out of 5]

I know Erastothenes for the Sieve of Erastothenes, which is a way to find prime numbers. It's interesting to read about his work in finding the circumference of the earth.

The book gave us pronunciations for Erastothenes, Cyrene, and Syene but not Ctesibius, Herophilius, Ptolemy, or bematist.

The book says "Perhaps he imagined the earth as a grapefruit." Unfortunately, grapefruit wouldn't exist until the 1700s. It's not a bad analogy, but it's not one that Erastothenes could make.

There are a couple of instances where the tone of a sentence stood out to me as noticeably less formal than the rest of the writing. That threw me out of the story.

Overall, a good book to read when studying geography or Ancient Greece.

[Jennifer Heise · Rating 5 out of 5]

Of course I had to read this, it's about a librarian (he became a librarian in the Library of Alexandria because of his love of making lists), but he was also a mathematician (my undergrad major).

Add to that the fact that it shows clearly how he measured the circumference of the earth, and puts to bed the old baroque lie that the people before Columbus believed the earth was flat.

And he's clearly shown as a person of color!

[Gayla Shomler · Rating 5 out of 5]

Geometry was never so interesting as in this story about how Eristothenes so brilliantly measured the earth over 2,000 years ago. Furthermore, it helps to see how math can be incredibly practical. Interestingly written story of a truly amazing person.

I would read this book to children fourth grade and up. Even a high school geometry student would learn from this interestingly written story.

For teachers, this is the perfect example of the essence of John Dewey's approach to learning.

[drowningmermaid · Rating 3 out of 5]

Wordy.

Biography of Eri-eri- that one guy who figured out the earth's circumference even though he lived 2000+ years ago. I thought he used an eclipse but it doesn't go into that. Not particularly fond of the way he's described as an uber-genius from the time he was a baby, makes use of words that I-- as an adult-- did not know ("bematist?"), and the math wasn't simple enough for a beginner to really grasp despite avoiding a lengthy explanation of pi. Good art, though.

[Samantha Mairson-Dougherty · Rating 4 out of 5]

Love the author’s note, which describes the author’s historical research. Lovely illustrations and informative copy. Don’t love the font and text placement / contrast on all pages. Some pages are not highly accessible because of the lacking contrast (e.g. dark blue sky and black text). Illustrations give a tremendous sense of place and leave a lot of room for discussion. Fabulous message to young readers about curiosity, math and asking big questions.

[Sandy · Rating 5 out of 5]

This book is a celebration of curiosity and how applying known pieces of information - such as geometry - can be used to solve complicated problems. I recently introduced this book to my 5 year old. The math is way over his head. But, I like that he knows the history of this important historical scientist and is beginning to understand how math can be applied. We will return to this book as my kids grow.

[Julie Tate · Rating 5 out of 5]

A delightful picture book that is a biography of Eratosthenes who from his innate curiosity sought to know more and learn. This book depicts a curious, active child - not your typical "be still and listen" type. With his curiosity he grows in wisdom and knowledge, and so did I as we read this book. This a great book for any age, but especially nice for upper elementary students who are just too wiggly and ADD to sit and read a longer - just print - biography.

[Annie Jackson · Rating 5 out of 5]

Wonderfully written and illustrated picture book about the brilliant Eratosthenes, head of the Library of Alexandria. My kids enjoyed learning about the use of geometry and shadows to estimate the circumference of the earth. Also sprinkled in were interesting facts about the ruler of Egypt and various other scientists, as well as some explanation of the Library of Alexandria and the surrounding culture.

[Jessie · Rating 3 out of 5]

The book starts in Eratosthenes's childhood, so it starts with a lot of speculation. It establishes the theme of curiosity and asking questions early on in the book.

I thought the explanation of how Eratosthenes estimated the size of the Earth was well done.

This was more heavy on words than a lot of similar picture books.

[Mitchell Friedman · Rating 3 out of 5]

A bit too fictionalized to be a biography. It does give the flavor of the truth. But even the idea that to do science requires you be a smart baby I find troubling. No matter. It was a pretty good story with good enough art. A bit too many words for a picture book. A bit too fanciful for a reference book. 3.5 of 5.

[Heidi · Rating 5 out of 5]

A great story with colorful illustrations, making the discovery of the circumference of the Earth accessible to even very young readers. I also liked that one of the most admirable traits of the main character was his love of asking questions.