There are many teaching designs in the fourth unit of the second volume of the third grade mathematics.

Teaching content:

Teaching objectives:

1. Feel and know the mass units of kilograms and grams, and know the actual mass of 1 kilogram and 1 gram.

2. Master "1kg = 1000g" and make a simple conversion.

3. Experience the connection between mathematics and real life, feel that mathematics is around, cultivate application consciousness and improve problem-solving ability.

Teaching emphases and difficulties:

1. Establish the concepts of 1 kg and1g. ..

2. Estimate the weight of some items.

Teaching process:

(A) create a situation to perceive the seriousness

1. Teacher: Students, two students did very well last class. The teacher should give them a warm hug.

The teacher picked up a particularly thin student at once, but couldn't pick up a fat student.

Teacher: Just now, the teacher hugged these two students. What did you find?

Teacher: Really? (Let a student try to hug again)

2. The teacher asked the students to take two items from the table and weigh them, saying who is lighter or heavier.

(2) Explore new knowledge

1. Report the information collected before the exchange class.

Teacher: Just now, we can roughly compare the weight of two items by hugging and weighing, so what should we do if we want to know the weight of the items?

Look at the net content marked on the package. Weigh with a scale. )

Teacher: Both methods are good! If the package of an item is marked with quality, we can know the quality of some items. Yesterday, the teacher arranged for students to go to the store to choose five kinds of foods they like to eat and investigate their net content. Who will report it?

Student report.

Teacher: The materials collected by students are very good! The grams and kilograms mentioned by the students just now are international unified quality units, which are used to express the quality of goods. Today, we will know grams and kilograms! (The teacher writes on the blackboard on the topic "grams and kilograms")

2. Know the scale.

Teacher: You can directly know the quality of items by looking at the net content marked on the packaging bag, but many items are unpacked. For example, I want to know the weight of two students, the eggs and apples on the table just now. What should I do?

(weigh with a scale. )

Teacher: Yes, if you want to know the exact quality of the goods, you can use the scale. Which scales have you seen in your life? Where have you seen it?

Health news: platform scales, platform scales, electronic scales, scales, spring scales, scales, health scales and so on.

Introduce the simple use of various scales with courseware.

Platform scale: put the goods in the plate and the pointer will tell us the quality of the goods.

Electronic scale: putting the goods into the tray will automatically display the quality of the goods.

Spring scale: You can read the mass of an article by hanging it on a hook.

Balance: We can calculate the mass of items in the left plate by calculating the weight in the right plate and the scale indicated by the scale below.

Scale: calculate the weight of the weight and the weight indicated by the scale, and we can know the quality of the weighed items.

3. Briefly introduce the usage of balance and weighing pan.

Teacher: There is a balance and a platform scale on each group's desk. The teacher briefly introduced the names of all parts of the balance: tray, beam, ruler, pointer, screw, weight ... (pointing to talk)

Teacher: The way to use the balance is to put the items to be weighed on the left plate first, and then put the weights on the right plate until the pointer of the balance is in the middle of the scale. At this time, the balance of the balance means that the two ends are equal in mass, and the sum of the weight in the right plate and the scale indicated by the scale below is the mass of the items in the left plate. The teacher debugged the balance on the students' desks. When using, put the weight on the right and the items on the left. Open the red weight box, which contains a pair of tweezers. You must clamp the heavy object with tweezers. You can't just hold it with your hands. If you hold it directly by hand, it will corrode the weight. Now use tweezers to pick up each weight and understand the quality of each weight.

Students know the weight in groups.

Teacher: Now the teacher puts the weight of 1 gram on the plate of the platform scale to see what has happened to the pointer of the scale.

Teacher: The pointer points to1g. Now students choose weights with different grams to see where the pointer is, and that place is the weight.

4. Know Dick.

(1) weigh it.

Teacher: Just now, we learned about scales and bench scales and learned how to use them. Now let's weigh the apples, salt, some soybeans and some paper clips on the table with a scale or balance. After weighing, students write down the name and quality of the goods and make records. See which group of students weigh the most items in 3 minutes, and which group is the winning group! Students weigh items in groups.

(2) say it. The weight of these items you weigh.

Teacher: For these lighter items, the students all use grams as the unit. Very good! Grams are represented by the letter g. (The teacher said while writing on the blackboard: Gram-Gram)

(3) Take a look.

Teacher: Do you know how much 1g weighs? Take out what you just called 1 g, such as a 2-cent coin, and put it in your hand to feel 1 g. How do you feel?

(4) looking for.

Teacher: Find out which things in life have a mass of about 1 gram.

Teacher: Students can experience the quality of 1 gram with their personal belongings, which is great!

(5) guess.

Teacher: Students, stop weighing. Guess how many soybeans have a mass of 1g? How many grains of rice is about 1 g? The mass of several paper clips is about 1 g. ..... guess and weigh again, right?

Students work in groups and exchange reports.

(6) estimation.

Teacher: Please select 3-4 items in the group and put them together. First estimate their quality, and then verify whether the estimation is accurate. Let's see who has the best estimate!

In-group verification, compare whose estimation is the most accurate.

5. Know kilograms.

(1) introduced by the teacher.

Teacher: Just now, some students in the group said that the combined quality of the goods reached 1000 grams or more, or even more than 2000 grams. Is it inconvenient to write a lot of numbers when recording? If you don't pay attention, you may make mistakes. What should we do?

Teacher: I find some students in our class very clever. According to the pre-class survey, heavier items should be expressed in kilograms. Very good! Lighter items can be measured in grams. Weighing heavier articles should be in kilograms, and kilograms should be expressed in kilograms. (The teacher said blackboard writing: kg-kg)

Teacher: The student just said that one bag of salt is 500g and two bags of salt are 1 kg. One bag of milk is 250g, and four bags of milk 1kg.

(2) Take a look.

Teacher: Please weigh two bags of salt or four bags of milk and feel the weight of 1 kg.

(3) looking for.

Teacher: 1 kg, which is what we usually call 1 kg, which is 2 kg. So what else can you find around you with a mass of 1 kg?

(4) pick it up.

Teacher: Please feel free to weigh a few kilograms, and then carry them by hand.

Some students collect all the salt from several groups and carry it, while others weigh their schoolbags and carry them again. ...

(5) say it.

Teacher: Please talk about the quality of familiar things in life in grams and kilograms.

6. Teaching 1kg = 1000g.

Teacher: Just now we already know grams and kilograms, so what is the relationship between grams and kilograms? How many grams is 1 kg? Please guess and try to verify!

(3) Summary

Teacher: What have you learned here?

(4) Consolidate exercises

1. Show the pictures on page 20 of the textbook.

Teacher: What is the quality of the following items?

(1) Instruct students to look at the scale on the first scale.

Teacher: From the scale surface, how much can this scale weigh at most? How much do two eggs weigh? How much does an egg weigh?

(2) The second question is done by myself.

2. "Exercise" on page 20 of the textbook.

Let the students fill in the textbook directly and revise it collectively.

3. Think about page 20 of the textbook.

1kg cotton or 1kg iron, which is heavier?

The company used the wrong diary.

Teacher: Teacher, here is a diary. Please read it carefully. What can you find?

Get up in the morning, lie in a 2000-meter-high bed, brush your teeth with a 18 decimeter toothbrush, wash your face, sit at an 8-meter-high table, drink a cup of milk 150cm high, eat a 65 kg egg, and then go to school with a 3 g schoolbag on your back.

Teaching content: How much is 1 ton (cognitive ton)?

Teaching objectives:

1. According to the specific situation, feel and know the mass unit ton, and know the weight 1 ton.

2. Master "1t = 1000kg" and make a simple conversion.

3. According to the specific situation, improve the ability to estimate the quality of objects and feel the connection between mathematics and real life.

Teaching emphases and difficulties:

1. Establish the concept of 1 ton.

2. Improve the ability to estimate the mass of objects according to specific conditions.

Teaching process:

(A) create a situation to guide the inquiry

1. Story introduction.

Teacher: Have you heard the story "Cao Chong called an elephant"? Who will tell you something? Other students must listen carefully and answer the questions after listening to the story! The teacher can then show a wall chart or multimedia picture and ask a classmate to tell the story of "Cao Chong is an elephant". )

Teacher: The story was told vividly and the students listened carefully. Think about it. How much does this elephant weigh?

Students may answer: it must be heavy, and it will be measured in grams, kilograms, or tons; Some people may also question: How many kilograms is that? )

The teacher leads the students to think: Do you think it is appropriate to explain the weight of elephants with the mass units grams and kilograms we have learned?

Ton is a large unit of mass, so what is 1 ton?

(Leading topic: 1 ton? )

(2) Explore communication and perceive new knowledge.

1.( 1) Which objects have a mass of 1 ton? The teacher uses courseware (or pictures) to show the situation map one by one, so that students can have a look and calculate.

350×3= 1050 (kg) Three buffaloes weigh about 1000 kg.

100×10 = 1000 (kg)10 barrel of oil weighs about1000 kg;

50×20= 1000 (kg) 20 bags of flour weigh about1000 kg;

25×40= 1000 (kg) 40 people weigh about 1000 kg.

(2) Group report.

The teacher answers the blackboard according to the students: 1t = 1000kg, and the introduction is expressed in letters: 1t = 1000kg.

2. Get in touch with life and learn new knowledge.

(1) shows that many objects in life need to use the mass unit ton.

Ask the students to say the meaning of each picture, and the teacher adds.

(2) Ask students to give more examples from their lives and analyze them together.

(3) Comprehensive application, integration and expansion

After finishing the exercises in the book (rearranging the order of exercises), the teacher will patrol and guide the students with learning difficulties.

1. Fill in the appropriate units (grams, kilograms, tons): Question 3.

2. Fill it in. Question 1

4 kg = () g 3 tons = () kg

5000 grams = 2000 kilograms

18t = () kg () kg = 6t

After the students finished speaking, the teacher showed the works on behalf of the students by physical projection and revised them collectively.

3. Students finish the second exercise independently, and then talk to their deskmates about their thinking methods.

Fill in ">"

8,000 kg, 8 tons, 4,500 g, 4 kg

3 tons ○3600 kg

Students think independently and then give feedback. Ask several students to report their thinking methods.

4. Math stories.

(1) estimation.

Just now, the students listened to the story "Cao Chong called an elephant". Let's have a look. How many times did Cao Chong weigh it? (wall chart or multimedia presentation)

The stone on the ship was weighed eight times before it was finished. The record table is as follows:

What time is 1 2 3 4 5 6 7 8?

Mass/kg 280 220 250 300 230 250 270 350

Do you know how much this elephant weighs? Please look at the record sheet. Let's make an estimate first Give students time to think and then report to them.

(2) Ask the students to discuss: Why does Chong use this method as a symbol? Do you have a better idea?

How much does this elephant weigh? First calculate the weight of the elephant independently, and then exchange the calculation results in the group.

Each group reports the calculation results.

Collective feedback, reflection and summary

What did you learn from this course?

Teaching content: Exercise 4-kilogram, gram and ton exercise class (1)

Teaching objectives:

1. Consolidate the understanding of kilograms, grams and tons, and further understand the weight of 1 kg, 1 gram and 1 ton.

2. Solve practical problems related to kilograms, grams and tons in combination with real life, and feel mathematics and reality.

The connection of life.

Teaching emphases and difficulties:

Solve practical problems related to kilograms, grams and tons in combination with real life.

Teaching process:

(A) the introduction of dialogue

Teacher: What quality units do we already know? What English letters do they use?

(Ask the students to answer in a certain order)

What is the forward speed between tons, kilograms and grams?

(plate: 1t= 1000kg, 1kg= 1000g)

Today we will use these quality units to have an exercise class.

(2) Instructing exercises

1. Display: fill in ○ > <; Or =

3t○4000kg 4kg○4t 6t○6000g 8kg○20k g

Ask the students to discuss what symbols should be filled in and why.

For example, 3t < 4000kg because 1t = 1000kg and 3t = 3000kg.

"Exercise 4" Question 3

Students fill in independently. What do you think when you communicate in class?

2. Exercise 4 question 1

Show the illustrations and let the students observe the scales carefully. Pay attention to the mass unit used by each scale. Students fill in the form independently first, and then communicate with the whole class. During the communication, the teacher once again stressed the need to pay attention to the measurement units marked on the platform scale.

3. "Exercise 4" Question 2

Let the students talk about their own ideas with examples in life.

4. "Exercise 4" Question 4

Let the students do it independently, and talk about their own ideas when communicating.

5. "Exercise 4" Question 5

Students read the questions, understand the meaning of the questions and finish them independently. Talk about your thoughts when communicating.

Formula: 9÷3=3 (yuan)

6. "Exercise 4" Question 6

Students read the questions, understand the meaning of the questions and finish them independently. Talk about your thoughts when communicating.

Formula:1000 ÷100 =10 (g)

7. Exercise 4 Question 10

Let the students understand the pictures and think independently, and then organize the class to communicate.