The characteristics of primary school students' thinking are the gradual transition from concrete thinking in images to abstract thinking, accompanied by certain intuitive action thinking. In the process of acquiring knowledge, the students of this class closely contact with their real life, use intuitive hands-on means to establish the appearance of 1 cm length, measure and practice in connection with real life, and let the students operate and think at the end of open practice.

2. Establish representation and cultivate students' spatial concept.

Pay attention to the fact that students create a representation of 1 cm in their minds, and the process of creating this representation is an active process for students to constantly perceive, think, measure, judge and verify. By estimating first and then measuring, strengthening practice, deepening representation, gradually forming spatial imagination ability and enhancing spatial concept.

3. Pay attention to cooperation and exploration, and cultivate innovative consciousness.

Know the scale line of your ruler, establish the representation of 1 cm, find 1 cm or several centimeters on the ruler, and then practice measuring the length of the object in cooperation with the group. Teachers patrol guidance and correct students' mistakes. In addition, it also pays attention to cultivating students to solve practical problems in life from different angles, directions and sides, thus cultivating students' innovative consciousness.