Three-dimensional target

One. Knowledge and skills

Further consolidate the concepts of positive and negative numbers; Understand that in the same problem, the quantity represented by positive numbers and negative numbers has the same meaning.

Two. Process and method

By analogy, positive numbers and negative numbers are used to represent quantities with opposite meanings around them, and then they are found to have the same characteristics.

Three. Emotional attitudes and values

Encourage students to think positively and stimulate their interest in learning.

Emphasis, Difficulties and Keys in Teaching

1. key point: correctly understand the concepts of positive and negative numbers, and be able to use positive and negative numbers to represent quantities with opposite meanings in life.

2. Difficulties: the comprehensive application of the concepts of positive and negative numbers.

3. Key points: Through the further analysis of examples, students can realize that positive numbers and negative numbers can be used to represent quantities with opposite meanings in real life.

training/teaching aid

Projector.

teaching process

Fourth, review the introduction of questioning class

1. What is a positive number? What is a negative number? For example, are there any numbers that are neither positive nor negative?

2. If a positive number means a profit of 50,000 yuan, what does-8,000 yuan mean?

Verb (abbreviation for verb) newly granted

Example 1. Within a month, Xiaoming gained 2 Jin, Xiaohua lost 1 Jin, and Xiao Qiang's weight did not change. Write down their weight gain this month.

2.200 1 The changes in the total import and export volume of countries below are as follows:

The United States decreased by 6.4%, Germany increased by 1.3%, France decreased by 2.4%, Britain decreased by 3.5%, Italy increased by 0.2% and China increased by 7.5%.

Write the growth rate of total import and export of these countries of 200 1.

Analysis: add a negative sign before a number to represent a number with the opposite meaning to the original number. Negative is only relative, and increasing-1 means decreasing1; An increase of -6.4% means a decrease of 6.4%, so under what circumstances is the growth rate zero? When it was the same as last year, the growth rate was 0.

Solution: 1 Xiaoming gained 2 Jin this month, Xiaohua gained-1 Jin, and Xiao Qiang gained 0 Jin.

2.200 1 year, the growth rates of the total import and export of the six countries are as follows:

USA -6.4%, German 1.3%, French -2.4%, British -3.5%, Italian-0.2% and China-7.5%.

Induction: In the same question, positive numbers and negative numbers have opposite meanings. For example, a profit of-2,000 yuan means a loss of 2,000 yuan; -3 meters forward means 3 meters backward; Waste-14 yuan means saving 14 yuan; Going south -7 meters means going north-7 meters, so making a profit of 2,000 yuan and making a profit of-2,000 yuan have opposite meanings.

Sixth, consolidate practice.

1. The eighth question on the fifth page of the textbook.

Hugging: An increase of -3.4% means a decrease of 3.4%, so the service exports of China and Italy of these six countries have increased this year, while those of the United States, Germany, Britain and Japan have all decreased, with Italy increasing the most and Japan decreasing the most.

2. supplementary exercises.

If you go west10m, mark it as-10/0m. If a person walks 12 meters from A and then walks-15 meters, can you tell where this person is at the moment?

Solution: If you go west 10 meter, record it as-10 meter. Then this person goes east 12 meters, and then goes west-15 meters, which means that this person goes east from A by 65,438 meters.

Seven. Course summary

Through the study of this lesson, do you have a further understanding of the concepts of positive numbers and negative numbers? Please use positive and negative numbers to indicate the quantity with opposite numbers around you.

Eight, homework arrangement

1. Exercise on page 5 of the textbook 1. 1, questions 4, 5, 6 and 7.

Nine, blackboard writing design

1. 1 positive and negative numbers

Second lesson

1, review and consolidate, and illustrate with examples.

2. Practice in class.

3. summary.

4. Homework after class.

X. after-school reflection