If it were an experienced teacher outlining their own theory, it would be an easy task.
Zhao Yi was not this experienced.
He read several books on teaching and studied the contents of undergraduate physics and mathematics elective courses, roughly charting out his teaching path, which was similar to writing a book--
First, there's the overview of the theory.
Then it's about understanding the purpose of studying the theory and exploring the renowned theories in current theoretical physics.
Latterly, the main content involves an in-depth introduction to the theory and a comprehensive analysis of its applications.