1, Reflections on the Teaching of Length Units

As soon as the new semester begins, the second-grade mathematics encounters a difficult problem-length unit. Although they came into contact with such words as "meter" or "centimeter" in last year's research, they still don't know their true meaning. This is the first time they have formally studied the unit of length. This is new knowledge for them, but it is an old experience in daily life. So I hope to do the following in this course:

1. Building a new knowledge framework based on the original knowledge and experience, we find that mathematical knowledge comes from life and is close to us.

2. Correct the wrong cognition of old experience and establish the length concepts of 1cm and1m..

3. By establishing a connection between the two, we can use new knowledge to measure the objects in life. Can test and deepen the understanding of new knowledge with old experience.

So according to the above knowledge, I will determine the teaching objectives and difficulties of this unit as follows:

1, so that students can experience the formation process of the length unit, realize the necessity of the same unit and know the function of the length unit. The first lesson is mainly to let students observe that I use different standards to measure ribbons with the same length. The conclusion is different through the discovery, which leads to "Why do ribbons with the same length have different results?" Let students perceive "the necessity of unified measurement standards". Then let the students do it themselves and verify our common conclusion at the same table.

2. In the activity, make students know the length units of centimeters and meters, and initially establish the length concepts of 1 cm and 1 m, knowing that 1 m = 100 cm. In order to help students establish the concept of length, I take three steps: first, let students know the ruler and make it clear that 0 to 1 on the ruler is 1 cm. Ask the students to find another 1cm on the ruler. For example, 1 pair 2, 2 pair 3. Finally, look for 1 cm around you, such as fingernails and thumbtacks. The concept of length unit of 1 cm is constructed with the help of specific foods.

3. Let students learn to measure the length of two objects with a ruler. Because there is no physical projector and students are not invited to demonstrate the measurement method, the centimeter is too small to be seen on the blackboard. So I have to adopt the teaching method of combining my own correct demonstration, students' imitation with my own wrong demonstration and students' correction.

4. On the basis of establishing the concept of length, cultivate the consciousness of estimating the length of objects with snow depth. In teaching, I pay special attention to the teaching of estimation. I ask students to estimate first and then measure. This can cultivate and improve the methods and accuracy of students' estimation.

5. Students know the line segment, learn to use the scale and draw the length of the line segment. I mainly choose the way of deskmate cooperation. After a painting is finished, ask your deskmate to help him measure it again to ensure that the other person draws the correct line segment.

Some ideas:

1. Without multimedia, students don't have enough experience to measure objects with various standards. Therefore, in homework, individual students will make mistakes when calculating how many cubes an object has. The necessary understanding of the same measurement standard is not very profound.

2. Confusion between centimeters and meters. One is the confusion in language, and the other is the confusion in the concept of length.

3. The measurement requires starting from zero, but I hope the child can calculate the length of the measured line segment without starting from zero.