Teaching is not the same as talking at students -- it is the deliberate design of experiences that help someone learn something they could not do before. A teacher plans what will be taught, decides how it will be delivered, manages the people and environment in the room, and checks whether learning actually happened. Subject expertise matters, but it is not sufficient: a brilliant mathematician can still fail to teach math if they cannot break ideas into steps, read confusion on students' faces, or hold a room's attention. Effective teachers share habits -- they plan backward from what students should be able to do, they check understanding constantly instead of assuming it, and they treat classroom management as part of teaching, not a separate chore.