Mr. Munroe, 31, said the project appealed to him. He recalled as a child a foldout diagram showing different animals at the starting line of a race and then sprinting/flying/crawling to show the different speeds of different species. “For some reason, I fixated on that illustration,” he said. “It stuck with me my entire life.”

Mr. Munroe said he hoped his drawings would break up the monotony and pace of a typical textbook. “I’m hoping it will be, ‘Oh, here’s a kind of fun and unexpected component,’” he said.

Inspired by his popular comic, “Up Goer Five,” THING EXPLAINER is a series of brilliantly — and simply — annotated blueprints that explain everything from ballpoint pens to the solar system using line drawings and only the thousand most common English words.