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A lesson in school is a planned period of time for (1) **learning**. It involves one or more students being taught by a teacher. A lesson may be either one section of a textbook or a short period of time during which learners are taught about a (2) **subject** or taught how to perform an activity. Lessons are generally taught in a (3) **classroom** but may instead take place in a situated learning environment.

Also, a lesson means a learner learning something he did not (4) **know** before. Such a lesson can be either planned or accidental, (5) **enjoyable** or painful. The slang phrase "to teach someone a lesson" means to punish or scold a person for a mistake they have made to make sure that he does not make the same mistake (6) **again**.