A yardstick is a measuring stick exactly one yard (three feet, or 36 inches) long. Teachers often keep yardsticks in their classrooms for measuring posters, marking straight lines on bulletin boards, or showing students how long a yard actually is. Unlike a flexible tape measure, a yardstick is rigid and flat, usually made of wood or plastic, with measurement marks along its edge.

The word also means any standard used to judge or measure something. When someone says “test scores aren't the only yardstick of intelligence,” they mean scores are just one way to measure how smart someone is, not the only way. A coach might use effort and teamwork as yardsticks for success rather than just looking at wins and losses.

This second meaning came from the physical tool: just as a wooden yardstick gives you an exact way to measure length, a figurative yardstick gives you a way to measure quality, progress, or value. If your teacher uses participation as a yardstick for engagement, she's measuring how involved you are by how often you contribute to class discussions.