In order to align with the theme of “Maths and Science Week”, a class management activity for S5 - “Pythagoras tree” design competition was organized. It is hoped that students can use the basic but important plane geometry - Pythagorean theorem as the basis, to cut and collage the Pythagoras trees of different angles with creative thinking. Principal Pang, who was a mathematics expert, was invited to be the judge and honorable guest at this event. Two classes were divided into seven groups. During the activity, students in each group discussed seriously the assignment of work, designs and cutting. They were energetic and enthusiastic in participating in the activity. The final products of each group had their own characteristics. In the end, four of the teams won the "Team Spirit" award, the "Distinctive" award, the "Pattern Design" award, and the "Color Matching" award respectively.