Josh Willett is a sixth-grader who loves biking, skateboarding and, most of all, computers. He practices coding after school and uses his laptop in every class. Every class, that is, except English.

Andrew Clements, a schoolteacher turned children’s author whose first novel, “Frindle” — about a mischievous fifth-grader who coins a new word for “pen” — was an unlikely bestseller about a kid’s ...