Expected learning outcomes:- Can identify the position of notes on the staffThe app for each difficulty is divided into two parts:Part 1: Study- App introduced that notes can be arranged "on the line" and "in space" of the treble and bass staves- Then, recognize the note positions of the "high notes" and "bass notes" staves respectivelyPart II: Exercises- All exercises are divided into three parts: "Treble Notes", "Bass Notes" and "Mixed Version".- One-star difficulty: place the note balls on the staff in sequence when prompted (less note balls)- 2-star difficulty: place the note balls on the staves in order when prompted (more note balls)- Three-star difficulty: According to the requirements of the question, find the position of different sounds on the staff