How to help students initially establish the concepts of positive and negative numbers
The purpose of teaching positive and negative numbers is to allow students to become more familiar with the meaning of positive and negative numbers through examples in daily life, and to use positive and negative numbers to express things in daily life. In the teaching process, we should carefully preset all aspects of teaching to provide students with a larger space for thinking, create a teaching situation that is close to students' cognitive rules and suitable for students' learning, and generate rich teaching resources for students' further learning. .
Positive and negative numbers are two opposite definitions. When teaching, we should focus on allowing students to conduct a comparative study of these two concepts, so that students can better understand the meaning of positive and negative numbers. The relationship between positive and negative numbers and 0 is a difficult point in teaching, and recognizing the position of zero between positive and negative numbers is the key for students to correctly understand positive and negative numbers. I think the following issues should be paid attention to during the teaching process.
1. The situational content is derived from real life, allowing for in-depth exploration of the problem.
"We often need to record data in our daily lives. Please record the scores of the basketball games of the following two classes." Using real-life situations as research materials, different records are presented. As a result, students' original cognitive status was revealed, and research on new issues was carried out on this basis. This not only allowed students to fully feel the necessity of studying the generation of negative numbers, but also adjusted teaching strategies according to the actual situation of the students in this class. Be well prepared to implement effective teaching.
2. Collect effective materials in life and feel the meaning of positive and negative numbers and the relationship between them.
In teaching, I think we should focus on collecting effective materials in life. Listen to the weather forecast; recognize it on the shopping receipt; read it according to the temperature in various places; give examples in real life... Let students realize that there are a large number of opposite meanings in life, and experience The close connection between mathematics and life. It is clear that positive and negative numbers represent two opposite meanings. On the basis of students' perceptual knowledge, it is further abstracted that positive numbers can mean increasing, higher than, positive direction, etc., while negative numbers can mean decreasing, lower than, and opposite direction.
In this lesson, we should also make full use of the thermometer as a teaching aid to "do enough work", read the temperature from the thermometer; try to write the temperature -5℃, -20℃; set the specified temperature on the thermometer ; Put the thermometer horizontally and abstract the number axis. These provide a very vivid basis for students to understand positive and negative numbers. When students learn, they can rely on concrete examples, and abstract concepts can be easily understood. The students gave full play to their main role in the activity and did not ignore their dominant position. They asked questions at key points many times: "Are the temperatures in Shanghai (4 degrees Celsius above zero) and Beijing (4 degrees Celsius below zero) the same?" "-5℃, - Who is lower or higher at 20℃? "What is the difference between +5℃ and -5℃"... During the activities, students not only do things with their hands, but also use their brains to think about problems. Through communication, students can master important mathematical ideas. and specific learning methods, the effectiveness of such mathematical activities is obvious.
3. Dig deep into the mathematical ideas and methods reflected behind the knowledge, and correctly guide students to understand the objective world.
If the content of negative numbers in life is not grasped well, it is easy to understand it one-sidedly, emphasizing only the negative numbers and ignoring the other side. Objective things are all interdependent. Without "positive", there is no "negative". Both aspects of things are indispensable. This is the basic view of dialectics. This kind of thinking should be conveyed to students through this teaching content, and it should be understood from such a height. Therefore, throughout the lesson, the teacher focused on the two opposite quantities for students to contact, understand, and study. Finally, at the end of the lesson, the students realized: "Forward and backward can be expressed by positive and negative numbers respectively." "Increases and decreases can be expressed by positive and negative numbers" "Amounts with opposite meanings can be expressed by positive and negative numbers"...the teacher's guidance is indispensable for such correct understandings and understandings.
Classification is the basic method of recognizing things. When people understand the things around them, they first classify them according to standards, then analyze them, and finally obtain a complete and clear understanding of them. The teacher also used the classification method when understanding positive and negative numbers, and focused on the issue of 0. During the classification, the students placed 0 in the position of "unclear". Through analysis and explanation, they came to the conclusion that "0 is neither a positive number nor a negative number."
The above designs have a broad perspective and are not limited to a local space set by the textbook. They gather resources extensively and fully develop them for my use. This eliminates the dullness of concept teaching in the classroom.