First, let students observe the objects in the study bag, and exchange the observed situation in the group, so that students can initially perceive the length of the objects and stimulate their interest in learning. Students may say that notes have different colors and so on. The teacher will guide or prompt during the inspection.

Second, explore the general method of comparing lengths through operation. Students may say the following methods: A. I can see that. B. The second one is shorter, because both ends are a little less than the first one. B. As long as students can understand the length of the object from their life experience, the expression is not necessarily accurate. The main purpose is to let students participate in the formation of knowledge.

Then show two pencils with different colors and different lengths to show the difference in length, further deepen the understanding of length and guide students to sum up who is longer and shorter than who from experience. Through group activities, let students experience the method of comparing the length of objects and participate in the formation of knowledge. Students use their own language to express who is long and who is short, and cultivate students' language expression ability.

Third, through game activities, let students experience the general method of comparing length and further deepen their understanding of the concept of length. Students can be guided to compare things around them, and they can also be prompted to compare how long each step took, who jumped far and so on. Teachers should participate in students' games, work with students, praise and affirm students with innovative spirit.

Students work in groups, and compare the length with objects or parts of the body in daily life, so that students can initially realize that there is mathematics everywhere in their lives. A set of exercises assigned by the teacher can further consolidate the knowledge learned, tell various comparative methods, distract students' thinking and cultivate students' imagination and innovative consciousness.

The following points should be paid attention to in the teaching of this class.

1. First of all, teachers should change their teaching concepts, give full play to students' main role, and let students operate, try to speak and explore new knowledge. Don't be afraid that students are not sure and don't ask too much.

2. It is better than anything to let students experience comparative ideas in activities and let them move freely.