What the first lesson is really doing
The first tennis lesson is rarely about strokes. It is about how a body moves toward a ball, and the coach spends most of the hour watching that one question being answered.
A coach who has taught for a while can read a player in the first ten minutes of footwork. Whether the player splits naturally before a contact, whether the eyes track the ball or the racket, whether the feet find space or wait for the ball to come to them. None of these need to be named in the lesson; they just need to be seen.
Almost no first lesson covers more than two ideas. A grip and a contact point, or a split-step and a rally, or a serve toss and a stance. The coach is choosing which two ideas to plant so that the second lesson has something to build on, not trying to fit a whole technique into sixty minutes.