Counting on Katherine tells the story of Katherine Johnson, the African American woman who calculated Apollo 13’s trajectory.

The book plays with the word “count.” It starts, “Katherine loved to count.” We see tiny Katherine Johnson playing with, and fascinated by, numbers. But “count” quickly assumes another meaning as Katherine counts on her father and then becomes the mathematician whom astronauts count upon.

I loved how elegantly Becker provides the necessary historical and scientific knowledge for young readers. Her explanations of the historical context are clear and simple:

“But back then, America was legally segretaged by race. her town’s high school didn’t admit black students–of any age.”

She also tackles the question of what Katherine actually did in her job using kid-friendly language:

“Sending a rocket ship into space is like throwing a ball into the air.”

And

“Because math is a kind of language, Katherine could ask those questions…”

And

“Katherine plotted the numbers she’d calculated on a graph. When she joined the points together, they formed a curved line. At one end of that line was Earth at the time the rocket ship launched. At the other was where Earth would be when the ship landed.”

Illustrations support the text, but ultimately Becker makes these explanatory passages look easy. But it’s not!

Back matter includes a list of sources. And don’t miss the end papers: chalkboards covered with math problems that many young readers will be able to tackle.

Counting on Katherine: How Katherine Johnson Saved Apollo 13 by Helaine Becker, illustrated by Dow Phumiruk. Christy Ottaviano Books: 2018.

Alyson Beecher hosts the Nonfiction Picture Book Challenge at kidlitfrenzy.com. Visit there for more great nonfiction picture books!