Teach you about the meaning and reading and writing of positive and negative numbers

Success points:

1. Pay attention to the creation of situations and understand the meaning of negative numbers. Students have some knowledge and experience with negative numbers before learning new knowledge, so I introduce weather forecasts that students are familiar with in teaching and let students be little weather announcers. At first, when some students read the temperature in Harbin, they read: Harbin is minus 27°C to minus 19°C. Although the student's reading was correct, I asked, is this what the weather forecast announcer said on TV? At this time, the students immediately changed it to: Harbin minus 27°C to minus 19°C, thus having a preliminary understanding of the meaning of negative numbers, teaching reflections "Reflections on Teaching Negative Numbers (Original)". In the following teaching, the teacher asked students to observe -3℃ and 3℃ and think about what each means. It follows that: 0°C represents the temperature at which fresh water begins to freeze. Temperatures lower than 0°C are called subzero temperatures. Temperatures higher than 0°C are called subzero temperatures. Above-zero temperature and below-zero temperature are represented by positive and negative numbers respectively, which reveals that the specific meaning of positive and negative numbers is to represent two quantities with opposite meanings.

2. Pay attention to the teaching of error-prone points. In the past teaching, students often made mistakes in comparing the magnitude of negative numbers. The reason was that the teaching content of the number axis was not in place. In teaching, I grasp the knowledge point of the number axis and make it clear to students that the numbers to the right of 0 are all positive numbers and the numbers to the left of 0 are all negative numbers. On the number line, the order from left to right is the order of numbers from smallest to largest. For example, the comparison between -2 and -4: because -2 is close to 0, so -2 is larger than -4.

Disadvantages:

1. In teaching, although students know that 0 is neither a positive number nor a negative number, due to the influence that the positive sign can be omitted, some students There is an error in writing with a positive sign in front of 0.

2. When it comes to marking negative fractions on the number line, it is easier for students to find positive fractions on the number line. However, for negative fractions, some students make mistakes in marking them. The reason is that students have poor understanding of negative numbers. There are also blind spots in knowledge in the order of arrangement.

Re-teaching design:

In future teaching, it is necessary to strengthen training on the comparison of negative numbers and finding negative fractions on the number axis, and strive to eliminate potential problems in the process of learning new knowledge. problem.