When prominent Barcelona-based illustrator Luci Gutierrez found herself tuning out in English class, she used her love of drawing to help retain what she'd learned. Ditching the kind of bland and useless phrases that fill most English textbooks, Gutierrez uses whimsical characters, cheeky dialogue, and even insults to bring vocabulary, grammar, and usage topics to life.

Nearly forty-seven million people in the United States speak a language other than English at...