Analysis of Typical Wrong Questions in Mathematics "Knowledge of Kilometers" in the third grade of primary school

The following is an analysis of typical wrong questions in the third-grade primary school mathematics volume "Knowledge of Kilometers" compiled by Kao.com for your reference!

◆Typical wrong questions:

Topic: The length of a car is 7 ( ), the length of the Yangtze River is more than 6,400 ( )

The Hangzhou Bay Cross-sea Bridge is 36 ( )

Students’ misunderstanding: The car is 7 (decimeters) long, the Yangtze River is more than 6,400 (meters) long

The Hangzhou Bay Cross-sea Bridge is 36 (meters)

◆Cause analysis: < /p>

1. Teachers focus on allowing students to establish the image of 1 centimeter, 1 decimeter, 1 meter, 1 kilometer, etc., but rarely practice estimation. For example, they show a length and let students estimate how long it is. Or give a length and let students draw it.

2. The students were too lazy to use the established concept of length to make accurate judgments, and just wrote a unit as they pleased.

3. Students lack life experience. For example, many people have never been to the Hangzhou Bay Cross-sea Bridge. The bridge in front of our house is indeed only a few dozen meters long, and there is no bridge over a hundred meters long. No wonder. For example, the length of the Yangtze River is more than 6,400, which is already a quite large number. They think that it is long enough in meters, but they find it incredible when it is thousands of meters. They are just imagining this question.

◆Teaching suggestions:

1. Help students establish corresponding concepts of length. It is important to understand the establishment of length units and not memorize them by rote. The understanding of length should be introduced through actual measurement and hands-on operations. Decimeters, kilometers, etc. are also generated from practice, and these units of length should be strengthened.

2. Usually, we should cultivate students' visual inspection ability. Not only is it 1 decimeter, you can also ask students to figure out how long 3 decimeters are, and how many decimeters a table is long. There are 1 kilometers, 5 kilometers, etc. from home. In teaching, through estimating, measuring, thinking, discussing, talking, and doing, students can establish the representation of these units of length and then develop their sense of space. You can set up activities such as "walking", "running", "taking a look" and "discussing" to experience "1 kilometer", so that students can fully understand "how long is 1 kilometer" Establish the concept of "kilometer" on the basis of.

3. Excavating materials in life helps students perceive kilometers. For the perception of kilometers, actual perception should be combined with the use of students' estimation abilities. For example, although some students walked around the playground and then imagined the length of 5 circles, or that 1,500 steps from home to a certain place is 1 kilometer, they still don't know how far 1 kilometer is. It's hard to estimate. In the process of forming the concept of a kilometer, the teacher can first ask the students to tell where it is about 1 kilometer from the school gate (the teacher must ride a bicycle to measure it in advance, and the answers should be diverse, and the students have indeed walked there every day) (perception), based on the initial establishment of the length of 1 kilometer, let the students estimate that it is about 2 kilometers from the school to where? How many kilometers does it take to walk from school to your home? (The teacher conducts random evaluations) Let students perceive the length of several kilometers. It takes about 15 minutes to walk 1,000 meters, but what about 2,000 meters? How far can you walk in 1 hour, and where can you walk from? A car can drive about 80 kilometers in one hour, so how long does it take to drive 800 kilometers?

Ask students to talk about their bus ride experiences in life, such as from where to where and how long does it take to ride? By combining it with practice, you can perceive the length. Perceive the actual distance corresponding to large values ??and large units. Help students establish familiar lengths in their minds for easy reference.

On this basis, teachers can also inspire and guide students to use things and scenes around them to describe the length of 1 kilometer or several kilometers, and connect kilometers with students’ normal life, so that Students' perception of kilometers goes through a dynamic generation process from fuzzy to precise. Teach students how to use reasoning, comparison, elimination and other methods to solve unfamiliar situations.