A jiè chǐ is a traditional wooden ruler historically used by Chinese teachers and parents to discipline children—typically by striking the palm—as a means of enforcing study discipline and moral self-restraint. The character jiè (戒) means 'to warn', 'to admonish', or 'to forbid', reflecting its purpose as a tool for correction and behavioral guidance; chǐ (尺) means 'ruler' or 'measuring stick', indicating its physical form. Though literally a measuring instrument, the jiè chǐ symbolized authority, seriousness toward learning, and Confucian values of self-cultivation through disciplined practice.

Today, the jiè chǐ is obsolete in modern education and appears mainly in historical narratives, literature, or museum exhibits. It evokes strong cultural associations with strict classical pedagogy—especially in private academies (sīshú) before the 20th century—and is sometimes referenced metaphorically to describe rigid, old-fashioned discipline.