A lesson in school is a planned period of time for learning. It involves one or more students being taught by a teacher. A lesson may be either one section of a textbook or a period of time during which learners are taught about a subject or how to perform an activity. Lessons are mostly taught in a classroom but they may take place online, or outside. Not all lessons are for children.
A lesson means someone learning something he did not know before. Such a lesson can be either planned or accidental, enjoyable or painful. The slang phrase "to teach someone a lesson", means to punish or scold a person for a mistake they have made making sure that they does not make the same mistake again.
