School texts contain over 85,000 distinct words. Luckily, students who understand how words are built can study one word and learn many for free. Word Explorer is a web-based game that teaches students to use the internal structure of words to understand advanced vocabulary. Learning to construct words from bases, prefixes, and suffixes and to connect them to meaning improves students’ ability to decipher and comprehend multisyllabic words. Building words builds vocabulary, a key component for reading comprehension.