Teaching plan for solving problems in primary school mathematics

1、 Teaching objectives

1. Understand that using positive and negative numbers to represent distance and opposite direction on a straight line can be used to solve practical problems.

2. Experience and explore the process of using positive and negative numbers to represent distance and opposite direction on a straight line, and develop core qualities such as geometric intuition, abstract consciousness, reasoning consciousness, etc.

3. Understand the close relationship between mathematics and life, and improve the interest in learning mathematics.

2、 Key and difficult points in teaching

[Emphasis] Use positive and negative numbers on a straight line to indicate the distance and the opposite direction.

[Difficulty] Establish mathematical model.

3、 Teaching process

（1） Import new lesson

Multimedia shows the theme map and creates a situation: the four students take the big tree as the starting point and walk in the opposite directions of east and west respectively.

Organize students to observe pictures and describe how everyone walks. Students can use direction and distance to express.

Teacher's guidance: they walk on a straight line in the east-west direction after the tree is located. How to use only mathematical symbols to indicate the distance and direction of their walking on a straight line?

Lead to the topic.

（2） Explain new knowledge

Question: In the past, you can simply use numbers to express distance by specifying the direction. What's the difference here?

Students can think of walking in the opposite directions of east and west in this situation, and the previous methods can not reflect the different directions.

Ask the students to think about how to use symbols to represent the east and west directions based on their recent knowledge. Students can think of positive numbers and negative numbers that can just express the opposite meanings.

Organize the group to discuss how to use positive and negative numbers on a straight line, and pay attention to the following points: ① which part of the straight line represents east and which part represents west, and how to distinguish them; ② How to show the distance on a straight line.

After the activity, find some student feedback. On this basis, teachers' blackboard writing standard construction model.

Take a point on the straight line to indicate the position of the big tree, as the boundary between east and west, and ask students what number to use.

Explain that as long as you specify which direction is positive, the opposite direction will naturally be negative. Let's assume that the east direction is positive, and the west direction is negative. Correspond the left and right of 0 with the east and west as well as positive and negative numbers.

First, it indicates the position where Xiaofang travels 2m eastward. Ask students to point out which side of 0 Xiaofang is located. In order to represent 2m, and to facilitate the later representation of 4m, take a length on the right side of the starting point as the unit length, which represents 1m. Then we can find the point representing+2m on the straight line, which is used to indicate the distance and direction of Xiao Fang's walking.

Organize students to show the distance and direction of the other three students.

Teachers and students review and reflect on the process of problem solving. Conclusion: positive and negative numbers can be used to represent quantities in opposite meanings. 0 is the dividing point.

Teacher introduction: In mathematics, numbers are often represented by points on a straight line with arrows. The number on the right of 0 is positive, and the number on the left of 0 is negative.