Rebecca Kai Dotlich is a poet and the author of many award-winning picture books for young readers, including Race Car Count; What Can a Crane Pick Up?; One Day, The End; and What Is Science?, which was a Bank Street College of Education Best Children's Book of the Year and a finalist in the Children's Science Picture Book category of the AAAS/Subaru the Best of Science Book & Film Prize. She lives in Indiana.

Sachiko Yoshikawa grew up in Tokyo, where her parents ran a salon. Her mother was a stylist, while her father kept track of the financials, often with an abacus. It was on the abacus that Sachiko learned to add and subtract. She still uses a mental image of her father's abacus when solving simple math problems. Sachiko is the illustrator of Beach Is to Fun: A Book of Relationships as well as What Is Science? She lives in California with her family.