Any of a wide variety of exercises, activities or devices used in the language classroom for realizing lesson objectives is known as—

In language teaching pedagogy (Anthony's framework), 'technique' refers to specific classroom activities, exercises, or devices used to achieve lesson objectives. 'Approach' is the theoretical foundation, 'method' is the overall plan based on the approach, and 'technique' is the actual implementation in classroom. Syllabus refers to the content outline. Techniques are the practical tools teachers use daily.