Teaching content: length-height ratio

Page 9- 10, complete questions 5-9 on page 12.

Teaching objectives:

1. Cultivate students' good habit of observing things carefully and realize that there is mathematics everywhere in life.

2. Make students realize that long and short are relative, and further establish a sense of comparison. In the process of comparison, if there are obvious differences, we can draw a conclusion directly. If there are no obvious differences, we can describe them by quantity and compare them.

3. In the process of different problem-solving strategies, students choose the most suitable method to cultivate their awareness of optimization.

Emphasis and difficulty in teaching: in the process of comparison, if there are obvious differences, we can directly perceive and draw conclusions; If the difference is not obvious, it should be described and compared by quantity.

Teaching preparation: both teachers and students prepare ropes, pencils, notes, toys, etc. Different lengths.

The teacher prepares: three villain cards of different sizes; Two bottles of soda and soybean milk of the same size.

First, situational introduction

1) Q: Do you like Conan in Detective? What might Conan do to catch the bad guys? Why? Because he observes things very carefully, he can see small differences. Today we will learn from his meticulous observation spirit and see who observes the most carefully!

Second, actively explore.

1, one of the activities

The teacher took out two ropes of different lengths and asked the students to observe them carefully:

Look what you found.

Can you describe them in a complete sentence?

2. Activity 2

A: The teacher took out two rulers with different lengths and asked the children to compare them to see who is longer than who and who is shorter than who.

B: Please take out a pencil for each child and compare them to see who is longer than who and who is shorter than who. (Talking to each other at the same table)

3. Activity 3

Teacher: Please compare each child's two little hands and see what you find.

Blackboard: The same length.

4. Activity 4

1. On the stage, the teacher arbitrarily pointed out that two students with different heights were tall and asked the children to say: Who is tall and who is short?

2. The teacher stood aside again: at this time, he asked his classmates: Who is tall and who is short at this time? Of the three of us, who is the tallest and the shortest?

(Students answer at will)

The teacher concluded: Height is relative, not absolute.

5. Activity 5

1, compare who drinks more.

Teacher: The teacher brought two bottles of drinks today. I want to buy two children a drink. Who wants to go?

Please compare their numbers first, then let the two children drink back to back, and then ask one of them:

(1) Who do you think drinks more than him? What do other friends think?

(2) Group discussion: Think about it, who is drunk? Why?

The teacher concluded: it's amazing to compare who drinks more with the remaining water!

Third, independent thinking: (student evaluation)

A: It is higher to have two students on stage (deliberately letting one of them stand on tiptoe). Students will immediately say "unfair". Teacher: Why is it unfair? Let the students understand that things should be compared at the same starting point.

B: 12 Page 5-9. Students finish it independently, and then revise it collectively to see who can get the little smiling face.

, self-evaluation.

2. Students evaluate each other.

3, the whole class evaluation