1. Guide students to know negative numbers in familiar life situations and read and write positive numbers and negative numbers correctly; Know that 0 is neither positive nor negative.

2. Make students learn to express some practical problems in daily life with negative numbers and experience the connection between mathematics and life.

3. Carry out patriotic education for students in combination with negative history; Cultivate students' good mathematics emotion and attitude.

Second, preview and guide before class:

1. What is a negative number? How to read it? How to write?

2. Give an example to illustrate what is a positive number? How to read it? How to write?

3. Where are negative numbers used in daily life?

Third, classroom learning and discussion:

I. Conversation and communication

Dialogue: Students, as soon as class begins, everyone will do a set of opposite actions. What is that? (Stand up and sit down. ) Today's math class begins with this topic. (On the blackboard: On the contrary. There are many natural and social phenomena around us that have the opposite situation. Look at the screen. The sun rises in the east and sets in the west every day; Someone got on and off at the bus stop; There are buying and selling in the bustling market; There are losers and winners in the fierce competition ... can you name some such phenomena?

B. Teaching new knowledge

1. quantities with opposite meanings.

(1) Introduce an example.

Dialogue: If you continue to "chat" along the topic just now, you will naturally enter mathematics. Let's look at a few examples (courseware demonstration).

(1) The sixth grade was transferred to six students last semester and six students this semester.

② Aunt Zhang made a profit 1500 yuan in February, and lost money in 200 yuan in March.

③ Compared with the standard weight, Xiaoming weighs 2.5 kg and Xiaohua is light 1.8 kg.

④ The water level of the reservoir rises by meters in summer and drops by meters in winter.

It is pointed out that when these opposing words are combined with specific quantities, they become a group of "quantities with opposite meanings". (Supplementary blackboard writing: quantity in the opposite sense. )

(2) try.

How can these quantities with opposite meanings be expressed mathematically?

Please choose an example and try to write a statement.

(3) show communication.

2. Know the positive and negative numbers.

(1) introduces positive and negative numbers.

Let's talk about it: Just now, some students wrote "+"in front of 6, which means 6 people are transferred, and adding "-"means 6 people are transferred (blackboard writing: +6-6), which is completely in line with mathematics.

Introduction: Numbers like "-6" are called negative numbers (blackboard writing: negative numbers); The number is: minus six.

"-"has a new meaning and function here, which is called "minus sign". +is a plus sign.

Like "+6" is a positive number, pronounced as: plus six. We can add "+"before 6 or omit it (blackboard writing: 6). In fact, many of the numbers we used to know were positive.

(2) Give it a try.

Please use positive numbers and negative numbers to represent another set of quantities with opposite meanings.

After writing, communicate and check.

3. Combine practice and deepen understanding.

(1) What do the numbers in the passbook mean? (Teaching example 2. )

(2) Combining with real life, a set of quantities with opposite meanings are given, which are expressed by positive numbers and negative numbers.