This document discusses teaching, testing, and their relationship in TESOL. It defines teaching as passing on accepted information to help students achieve objectives, while tests assess if objectives were achieved. Tests can positively or negatively influence teaching through "washback effect" - the extent tests impact what teachers and students do. Positive washback includes focusing on objectives and motivating learning, while negative includes ignoring untested topics and "teaching to the test." Good tests are valid, reliable, practical, comprehensive, and balanced assessments that provide useful feedback for students and help teachers identify strengths and weaknesses.