One Hundred Essential Things You Didn’t Know You Didn’t Know: Math Explains Your World

Barrow, John D.

Barrow, J. (2009). 100 essential things you didn’t know you didn’t know: Math explains your world. New York: W.W. Norton &.




John D. Barrow begins the book by emphasizing the presence of math all around us and encouraging the reader to use the book to become more aware of it. Then he discusses the cliché, “two’s company, three’s a crowd” and the hidden math implications behind the saying. The text continues to discuss the relationship of math in rugby, wagon wheels, the weight of boxers, the balance of a tightrope walker, the St. Louis Gateway Arch, collecting cards, and high jumping. Over 100 chapters, Barrow covers a wide range of topics from the refracted light rays that make a diamond shine to the pattern of leopard spots. Each chapter lasts only three or four pages, giving the reader a glimpse of the impact of math on the topic. Beneath each chapter title, Barrow inserts a quote from a famous musician, composer, author, poet, or book. The quotes spark the reader’s interest, particularly if he/she is a fan of the quoted celebrity. As a whole, the book succeeds in showing the reader the vast presence of math in many aspects of life. The author does not directly reference algebraic or trigonometric equations but rather ties numbers in to explain every day phenomenon. For example, in the card collecting chapter, Barrow reminisces about his own childhood when he collected motor cards. He asks how many cards should be bought in order to compete the set. Then, he considers the impact if friends pooled together in the card collecting endeavor. In the 100th chapter, the text concludes with the global village, a place with 100 people representing the scaled down population of the world.


Barrow uses short concise sentences without overly complex vocabulary, resulting in a Flesch-Kincaid score of 7.8. However, the ties to math concepts are suitable for an upper high school student. Topics such as the harmonic series, usually discussed in calc 2, and the confidence level calculated when making a prediction are thrown around without much explanation. Barrow’s goal is to make the advanced math student more aware of the use of his/her math knowledge. 7th or 8th grade students would not be able to understand the text because of their limited math exposure. For this reason, a high school Junior or Senior would have a much easier time reading the book. Even at this level, the student may need some help with the advanced calculus and statistics topics that may not be covered in school until the college level.

Use in Class

The vast array of topics covered in the text make it ideal for a project where students are able to explore a chapter that interests them. I would select the following chapters: Collecting Cards, High Jumping, and How to Rig an Election. Pairs of students would be able to select one of the chapters and would individually read the chapter then discuss. After each student has a full understanding of his/her chapter, the pairs will construct a project related to the chapter. For the collecting cards project, the pair would select a collectable card set and determine the number of decks needed to purchase that particular set depending on how many people are collecting. For the high jumping project, the pair would each try the two different high jumping techniques discussed in the chapter and calculate their center of mass height for each method. For the election rig project, the pair would come up with a fictional election with real or fictional candidates, select a candidate they would like to win, and come up with a math strategy for the candidate. Additionally, I would allow the students to look through the other chapters and come up with their own project relating to the chapter with my approval.

Unit Focus


Submitted by Courtney Trost

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