1、 Talk about the lesson standard

Today, my topic is Understanding Negative Numbers, which is the content of Unit 1, Volume 2, Grade 5 of Qingdao Textbook.

The Mathematics Curriculum Standard arranges the understanding of negative numbers in the knowledge system of "number and algebra" in the second learning stage, with the specific goal of understanding the meaning of negative numbers in familiar life situations, and being able to use negative numbers to express some problems in daily life. It can be seen from the Curriculum Standards that the learning of this unit is intended to make students feel the connection between negative numbers and life. There are no complex concepts and calculations, and the level of knowledge is relatively shallow. Therefore, I think that how to fully show the charm of negative numbers and stimulate students' interest in exploration is a problem worth paying attention to when teachers design this unit.

2、 Talking about textbooks

After studying the textbook carefully, I changed the original layout of the textbook. The textbook is based on the students' existing life experience, and selects the two familiar situations of "temperature" and "altitude" to let students know and understand negative numbers. In my previous teaching process, the effect was not ideal. Therefore, I have a bold idea: change the original arrangement, integrate the learning content, and "creatively use the teaching materials" instead of "teaching the teaching materials". Use the experience that students are interested in to teach. As the saying goes, interest is the best teacher. To this end, I have formulated the corresponding teaching objectives.

3、 On the Teaching Objectives

1. Knowledge and skills: understand that positive and negative numbers are actually needed, master the ability to judge whether a number is positive or negative, and initially use positive and negative numbers to represent quantities with opposite meanings.

2. In terms of process and method: through the learning of positive and negative numbers, students' ability to apply mathematical knowledge to solve practical problems is cultivated.

3. Emotion and attitude:

① . Introduce positive and negative numbers from practical problems, and then consolidate them through examples, so that students can feel that mathematical knowledge comes from life and is applied to life.

② According to the new curriculum standard, it is proposed to pay attention to the cultivation of students' basic mathematical thoughts. I want to infiltrate the dialectical thought of opposites and unity through the teaching of positive and negative numbers.

③ Through the introduction of knowledge about negative numbers, cultivate students' patriotic feelings.

4、 Talk about the key points and difficulties of teaching.

Teaching focus: understand and use positive and negative numbers to express quantities with opposite meanings.

Teaching difficulty: understand that 0 is neither positive nor negative, and be able to make a preliminary comparison of the three.

5、 Explain the teaching link and design intention

In order to achieve the above teaching goals, I have designed four teaching links, namely: 1. skillful setting of situations, perceptual introduction - leading to negative numbers; 2. Experience internalization, explore new knowledge - know negative numbers;

3. Return to life and expand application - apply negative numbers; 4. Classroom summary, knowledge extension - expand negative numbers. Next, I will elaborate on the teaching link and my design intention.

Before class, I prepared a warm-up game called "I'm anti anti, I'm anti anti, I'm anti anti anti", which has two intentions: first, it not only enlivens the classroom atmosphere, so that students and teachers can relax, but also has a direct connection with the negative numbers we learned today, which can quickly bring students into the meaning of "opposite", and pave the way for the next study. Now, let me talk about it

The first link: ingenious setting and perceptual introduction - leading to negative numbers

We all know that the classroom should be a torch to ignite the wisdom of students, and the kindling for her is a challenging question. So, I changed the original textbook to present the temperature teaching in three cities. At the beginning, I raised a question with high thinking value: "The teacher said a few things, recorded the data information you heard, thought independently, and chose the method you like to record. The key is to let others see it at a glance." These data information was carefully prepared by me: goals, goals, goals Transfer in and transfer out of students and profits and losses of business. The purpose of creating these three situations is twofold: First, these situations are familiar to students and more interesting than the temperature learning in the textbooks. 2、 These situations imply the focus of this unit, and positive and negative numbers are used to represent quantities with opposite meanings. I preset the possible answers of students, such as "√" and "×", "smiling face" and "crying face". Of course, some students use positive and negative numbers. Although their answers come in various forms, they are all intrinsically related. I then asked a valuable question: what you just said can only be understood by yourself. Can you find a unified recording method? So the learning goal in dynamic generation is to recognize negative numbers and use positive and negative numbers to represent quantities with opposite meanings. It's not surprising that "negative" is really a "timely rain"! With this introduction, students have their own internal needs of "finding a unified form", which

At the same time, students have experienced the process of symbolization and mathematization from concrete to abstract, and their understanding has gradually changed from vague to clear. This process allows students to simply experience the process of human exploration of negative numbers, realizing the recreation of mathematical learning.

After the introduction of negative numbers, I will directly describe what kind of numbers are called positive numbers and what kind of numbers are called negative numbers. As the saying goes, don't think that students are a blank sheet of paper and know nothing. Teachers should let go when they should let go, and let go when they should. When students know their concepts, they can quickly judge whether a number is positive or negative. Then, I stimulate students' thinking through the game of "quick answer and judgment", which can not only activate the classroom atmosphere, but also enable students to master knowledge skillfully. The students can also experience the mathematical ideas of infinity and correspondence of positive and negative numbers through the exercise of "You can write several positive and negative numbers". Now the new curriculum standard also focuses on strengthening students' basic mathematical thinking. I think here, these mathematical ideas have infiltrated invisibly.

The second link: experience internalization, explore new knowledge - know negative numbers

I used the courseware to broadcast the weather forecast of a certain day on CCTV, and asked students to record the above information to guide them to understand how to use thermometers to measure temperature in life, and preliminarily clarify the different expressions of above zero temperature and below zero temperature. After introducing the basic knowledge of thermometers, ask students to dial 4 ℃ in Shanghai and 4 ℃ in Beijing, that is, 4 ℃ below zero. Don't underestimate the link of students' dialing. Our textbook directly presents the temperature of the three cities and lets students read it by themselves. I creatively changed the teaching materials for two purposes: first, to change from static to dynamic, through a small "dial", it aroused deeper thinking: to express the temperature on the thermometer, first determine the position of 0 ℃. Let the students understand clearly: in temperature, 0 ℃ is the dividing point to distinguish between above zero temperature and below zero temperature. The temperature higher than 0 ℃ is expressed as a positive number, and the temperature lower than 0 ℃ is expressed as a negative number. Second, students' hands-on operation and interest

Ang Ran not only organically integrates positive numbers, negative numbers and zero into a new conceptual framework, realizing the re understanding of 0, but also highlights the teaching focus of this lesson, breaking through the difficulty that 0 is neither positive nor negative.

After students have rationally understood the above zero temperature and below zero temperature, I will show Harbin - 10 ℃, and guide students to think: which is colder than - 4 ℃ and - 10 ℃ in combination with students' life experience? Then show the coldest city in China: Mohe - 30 ℃ and the lowest temperature on the earth's surface: - 88.3 ℃. Use your expression and action to express the feeling of getting colder and colder. This not only infiltrates knowledge such as the comparison of negative numbers, but also embodies the concept of learning mathematics in life.

In the practice teaching of the number axis, we experienced teachers know that the number axis teaching is a difficult point. So, I took advantage of the thermometer teaching aid to place the thermometer horizontally and tell students that it is like a number axis, with 0 in the middle. Let students tell where the negative number is on the side of 0 and the positive number is on the side of 0. In this way, students can not only visually understand the relationship between positive, zero and negative numbers through the thermometer teaching aid, but also penetrate mathematical ideas such as interval and limit.

The third link: return to life and expand application - apply negative numbers.

Since negative numbers are found in life, we should "take them from life and use them in life". In the exercise section, I provided students with a lot of information in life, and used mathematical knowledge to solve their own problems in life, making the exercise both interesting and useful. I designed three exercises:

1. Basic exercises. For example, which key should I press to go to the fifth floor for a meeting or to the first floor underground? Students can see that this is indeed a problem we often encounter. Teachers can also use the altitude of tourist attractions at this time