1, let students use the temperature situation to understand the expression of positive and negative numbers, feel the necessity of introducing negative numbers, understand the expression of MINUS temperature in life, and read and write correctly.

2. According to the specific situation, let students experience activities such as watching, comparing, speaking, connecting and arranging, cultivate students' observation ability, generalization ability and logical thinking ability, cultivate students' sense of cooperation, and enable students to master the method of comparing two sub-zero temperatures.

3. Let the students know that there is a great difference between the north and the south in winter in China through activities such as small announcers. Let students experience the happiness of success in mathematics activities, feel the close connection between mathematics and real life, and cultivate students' interest in learning mathematics.

Teaching focus:

Use the temperature situation to understand the expression of positive and negative numbers, feel the necessity of introducing negative numbers and read and write correctly.

Teaching difficulties:

Will compare two sub-zero temperatures.

Resource utilization rate:

Schematic diagram of thermometer for electronic whiteboard courseware A glass of ice water and a glass of warm water.

Teaching process:

First, create scenarios and introduce new knowledge.

1. First listen to the teacher describe two scenes, close your eyes and these two scenes come to mind. How do you feel after listening?

Scene 1: The sun is scorching the earth, and cicadas are shouting in the trees. Although pedestrians in the street are wearing umbrellas, people are wearing short-sleeved shorts and people are still eating ice cream in their mouths, the sweat on their foreheads is still bubbling.

Scene 2: The cold wind is howling and snowflakes are flying all over the sky. People put on cotton-padded clothes, gloves and thick scarves, but pedestrians in the street are still tightening their necks and shivering.

2. Tell your feelings.

3. Introduction to the topic: Hot and cold means that the temperature is changing. In this lesson, we will learn about temperature.

Second, explore new knowledge.

(A) the expression of temperature

1. Listen to a video broadcast and make a clear request: record the temperature in Xi 'an and Xinjiang with colored pens in your favorite way.

2. Broadcast: Xi 'an 8℃ to13℃; Xinjiang-4 C to 5 C.

3. Teachers patrol to sort out students' expressions.

4. Show, communicate and compare several representations, and get+and-through optimization.

(1) what does this-here mean? (indicating that the temperature is below zero)

The teacher guides the students to observe and compare, and draws a conclusion that zero is relative with a symbol.

Meaning expression, this is the unique beauty of simplicity in mathematics!

② Here-is not a minus sign, but a minus sign, which is pronounced as-1 Celsius or-1 Celsius. What about 9 degrees Celsius above zero? (Write a+sign before 5℃) This+sign is called a plus sign here. What does this mean?

Blackboard writing: +5℃ -4℃ plus sign minus sign

③ Do you usually write+before 5℃?

It is concluded that+in front of positive numbers can be omitted, and-in front of negative numbers cannot be omitted.

What temperatures have you seen in your life?

(1) refrigerator door temperature display, knowing degree-day: Celsius℃

Celsius is a kind of temperature scale widely used in the world at present, which is expressed by the symbol℃. It was put forward by Swedish astronomer Anders Poerxiusi in the18th century. Later generations used the first letter C of his name to commemorate him.

(2) The average normal body temperature is between 36℃ and 37℃ (underarm). If it exceeds this range, it means a fever; If it is lower than 38℃, it means low fever; If it is above 39℃, it means a high fever. Above 39℃, it is dangerous.

Cognitive thermometer

What tools do people use to measure temperature? (thermometer)

It's amazing that a small thermometer can know the heat and cold. Do you want to know? (thinking)

(1) all kinds of thermometers, so that students can understand different styles of thermometers. (Courseware demonstration)

(2) Show commonly used thermometers for measuring room temperature by projection, so that students can observe them carefully. What did you find on the thermometer?

(3) report by name

① Unit temperature ② The red liquid column will increase or decrease.

(3) There is a scale of 0 in the middle, the temperature is above zero, and the temperature is below zero.

④ The cell of1is 1℃

⑤ Teacher profile ℉: Fahrenheit was set by German Warren Heiter in 17 14. Both Fahrenheit and Celsius are units used to measure temperature.

(2) Practice reading and writing temperature

1. Read the temperature displayed on the thermometer. (Show courseware) 15℃, 0℃,-15℃

2. Can students read thermometers? (Using the screen curtain function, three thermometers appear in turn. )

First say and write down the temperatures displayed on the three thermometers.

Randomly compare these three temperatures and tell who is the highest and who is the lowest.

(3) Sensing temperature

1. Show me the schematic diagram of the thermometer.

(1) Call the roll to ask students to read some books above zero and below zero respectively.

(2) Try to tell the readings on the thermometer with your eyes closed, and let the students initially establish a thermometer model in their minds.

(3) The teacher gives the following temperature, based on 0℃, and asks the students to indicate with their hands that the temperature is above or below zero.

8℃ -5℃ 15℃ - 15℃ -20℃

measure the temperature

(1) Show two cups: one is warm water and the other is ice water mixture.

(2) Estimate their temperatures first, and then measure the temperatures of two glasses of water with two thermometers at the same time.

3. Know 0℃

(1) Ask a student: How many pens did you bring today? (0)

What does 0 mean? (indicating no)

So 0℃ means no temperature?

(2) Name names to talk about the understanding of 0℃.

(3) Summary: Temperature indicates the degree of heat and cold of an object, and any object has a temperature. 0 degrees Celsius is only a numerical value in temperature, and it is also the dividing point between zero and below zero in weather, which physically represents the melting point of ice. Above 0 degrees, the ice began to melt into water; Below zero, water begins to freeze.

Scientists set the temperature of ice-water mixture to 0℃ at standard atmospheric pressure and read it as 0℃. The boiling water temperature is set to 100℃.

4. Connect the corresponding temperatures with wires. (Use the writing function of the whiteboard)

Above zero 12 centigrade 10 centigrade 16 centigrade.

- 10℃ + 12℃ - 16℃ 0℃

(1) Ask the students to read the temperature in the first row first.

(2) Report the connection by name.

5. Read the temperature, so that students can know that there is a great temperature difference between the north and the south in China at the same time.

Everyone did a good job. In order to reward everyone, the teacher decided to take everyone to Harbin to participate in the Ice and Snow Festival. (Courseware demonstration)

Wow! Everyone was shocked by the visual impact brought by the ice sculpture world!

(1) What was the temperature in Harbin that day? What about the temperature in other cities? Look at the screen

This is the temperature collected by the teacher in several major cities that day. Who can be an announcer and broadcast the weather to the whole class? (national map)

(2) Let students be small announcers to broadcast. (Use the searchlight function of the whiteboard)

(3) By comparing the temperatures in some southern and northern cities, we can know that the temperatures in northern and southern China are quite different at the same time.

Third, consolidate the practice.

1. estimate

(1) Show some local pictures of different seasons and connect them with appropriate temperatures. Let the students know the temperature in different seasons in our local area. (Connect the writing function of whiteboard)

Summer short-sleeved sweater coat cotton-padded jacket cotton shoes (ice and snow)

-8℃ 36℃ 19℃

2. Compare the temperature between -5℃ and -20℃. (Show the situational picture of Exercise 1 on page 88 of the textbook)

Name exchange report.

3. The table below shows the highest temperature in some cities in China given by the weather forecast. (Courseware demonstration)

(1) Which city is hotter, Beijing or Shenyang?

(2) Arrange the temperatures of these five cities from low to high. (Use the drag-and-drop function of the whiteboard to name students and arrange them)

Fourth, expand and extend.

Pointing at the blackboard: The highest temperature in Xinjiang is 5℃, and the lowest temperature is -4℃. What is its temperature difference?

(1) Let your deskmate discuss with the help of the thermometer schematic diagram. (2) Exchange reports. (3) induction.

Verb (abbreviation of verb) course summary

What did you learn from this course? What other puzzles are there?

Summary: There is mathematics everywhere in life. As long as we are willing to live, we can solve many problems in life with the mathematics knowledge we have learned.

Six, homework arrangement

1. Check the data after class and collect the temperature of some other objects.

(such as the temperature on the surface of the moon, the temperature on the surface of the sun, the melting temperature of some metals, etc.). )

2. Have you ever seen the number-besides some temperatures in life?

Collect some communication in the next class.