The third unit of the fifth grade mathematics volume of People's Education Press explores the law of the cube drawn on the surface in the picture. It is difficult for students to learn, which is also one of the major difficulties in this math book list.

The fifth grade refers to the senior stage of primary school. Students in grade five of the six-year program should prepare for the junior high school in grade six, so they should study hard and review what they have learned before to prepare for the junior high school exam.