Sun teaches three classes because the distribution of mathematics teachers in senior high schools in hainan overseas chinese middle school is arranged according to the needs of disciplines and teachers' abilities. According to the arrangement of the school, each class needs a math teacher to teach. As a high school math teacher, Sun has strong teaching ability, so she is assigned to teach three classes of math courses.

For Sun, teaching mathematics in three classes may face some challenges. Teaching more classes means that her workload of preparing lessons and correcting homework will increase, and she needs higher time management and organizational ability to ensure the teaching quality of each class. In order to meet these challenges, Sun can arrange his time reasonably, make plans for preparing lessons and correcting homework, make full use of classroom time to improve teaching efficiency, and keep good communication with students and parents to solve problems in time.

In addition, multi-class teaching also provides Sun with more teaching opportunities and challenges. She can improve her teaching experience and ability by teaching students in different classes, understand the learning characteristics and needs of different students, and constantly improve her teaching level. At the same time, she can learn from each other through communication and cooperation with other math teachers, thus improving the teaching quality.

Generally speaking, Sun teaches three classes according to the arrangement of the school and her teaching ability. She can arrange her time reasonably, communicate well with students and parents, meet the challenge of teaching multiple classes, and improve her teaching experience and ability through this opportunity.