Piano teacher is piano teaching equipment working with an app. It can calculate the score for students by detecting the black and white keys pressed and the intensity they are pressed with. It can also receive instructions from the app to teach students to play. It is elongated, semi-covered on the keyboard, compatible with all major piano. It detects the black keys by directly shot light and the white keys by reflected light. It has keys and finger ID LED. Introduction to piano teaching is often difficult and the learning process boring and one needs to spend long time practicing. This product used with a teaching app, offers recreation, can achieve a quick start and does not require any previous knowledge of its students.