The first part 1 to 5: The vast starry sky aroused the author's infinite reverie, and the author imagined that the other side of the universe was the reflection of this side.
The second part 6 to 9; The author has been immersed in a beautiful imagination, imagining the magical math class on the other side of the universe.
The third part is 10 to 12. The author shared his beautiful imagination with everyone, and everyone was fascinated by the world on the other side of the universe.