1, combined with the specific situation, realize that there are a lot of decimals in life.
2. Through practical operation, understand the relationship between decimals and decimal fractions, understand the meaning of decimals, and know the names and meanings of each digit in decimal parts, so that you can read and write decimals correctly.
Key points and difficulties:
Through practical operation, understand the relationship between decimal and decimal part, understand the meaning of decimal, and know the name and meaning of each digit in decimal part.
Teaching rules:
Group cooperation and exchange method, combination of lecture and practice method.
Teaching preparation:
Small blackboard
Teaching process:
First of all, an exciting introduction.
How long is the blackboard?
1, the teacher took out the meter ruler to measure the length of the blackboard.
2. The teacher wrote the actually measured length on the blackboard. The length of the blackboard in the textbook is 2 meters and 36 centimeters.
3. The teacher asked: How long is the blackboard?
4. Students summarize their own methods, communicate in groups first, and each group chooses representatives to report.
5. The teacher announced the answer.
Third, explain examples.
1, divide one meter into 100 parts on average, one part is 1 cm, 36 cm is 65438+36 meters per thousand, and expressed in decimal is 0.36 meters.
2. The total length of the blackboard is 2m+0.36m = 2.36m
3. Answer by yourself. What are the weights of quail eggs and ostrich eggs?
4. The teacher asked the students to answer.
Fourth, in-class training.
1, review the import and judge whether it is right or wrong. (displayed on the blackboard)
(1) Divide 1 into 100, and 10 is 1. ( )
(2) Divide 1000 kg into 1000 parts, with five parts being 0.005 kg. ( )
(3) Twelve percent is 0.02. ( )
(4) Seven tenths of a meter is 10.7 meter in decimal. ( )
(5)0.05 means five percent. ( )
(6)3.2 1 is three decimal places. ( )
(7) The score of 0.034 is ()
2. Write the following decimals. (9 points)
(1) The volume of the hive is almost 0.25 cubic centimeters. Writing: _ _ _ _ _ _ _
(2) The human eye can distinguish objects only 0.06 mm. Writing: _ _ _ _ _ _
(3) Mount Everest is the highest mountain in the world, with an altitude of 8844.43 meters.
Writing: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
3. There is a number. The tenth, tenth and thousandth digits are all 2, and the rest are all 0. It is (), pronounced (). (8 points)
4. Please use four numbers of 0, 3, 6 and 9 as required (each number can only be used once).
The integer part of (1) is the largest, and the number with one thousandth of 6 in the decimal part is ().
(2) If you don't read 0 and the decimal part has two decimal places, it is ().
(3) Read 0, the decimal part has only one decimal, which is not 0.
Verb (abbreviation for verb) assignment
Do questions 2 and 4 in the workbook and complete the related exercises.
1, complete the three exercises on page 4 of the textbook independently. The teacher corrects the answers collectively.
2. Complete the textbook exercise independently 1.
Blackboard design:
The meaning of decimal (3)
The Significance of Decimal Teaching Plan Part II Teaching Contents:
Compulsory Education Curriculum Standard Experimental Textbook (Southwest Normal University Edition), pages 69-72, examples 1, examples 2 and classroom activities 1, 3, 4.
Teaching objectives:
Let students know more about decimal and decimal counting units and understand the decimal relationship between two adjacent counting units.
Experimental objectives:
1, using multimedia courseware to stimulate students' desire to know and learn decimals.
2. Through intuition, operation, reasoning and other activities, let students clearly summarize the meaning of decimals, feel the close connection between mathematics and life, and realize the role of decimals in daily life.
Teaching preparation:
Courseware, meter ruler, ruler, etc.
Teaching process:
First, introduce new knowledge.
Courseware demonstration: students measure the length of the blackboard and the length and height of the desk.
1, students measure the length of the blackboard by themselves. Are the figures of desk length and height integer meters?
Teacher: In measurement and calculation, sometimes integer results can't be obtained, and they can usually be expressed in decimals.
2. Memories and exercises: 1 Angle =() 10 yuan =() 10 yuan = ()1DM = ()10m = () M3DM = ()10m.
Teacher: What else do students want to know about decimals? Writing on the blackboard: the meaning of decimal
Second, explore new knowledge.
1, teaching example 1
(1) Fill it out. (The courseware shows the example 1 1 picture) ① How should this picture be represented by fractions and decimals? what do you think? Say: 0? 7 means to divide a square into () parts and take () parts. 0? There are () zeros in 7? 1。 2 like 0? 1,0? 3,0? 5,0? 7 This decimal place refers to dividing the whole into 10 parts, taking 1 part, 3 parts, 5 parts and 7 parts respectively, that is, a decimal place represents a few tenths.
(2) Say it in the same way. The courseware shows the next two pictures. (1) Draw a box for 1, and draw 45 boxes for the second one. Expressed in fractions and decimals. what do you think? (2) Discussion summary: How many decimal places is the percentage? How many fractions do two decimal places represent?
2. Teaching Example 2 (Understanding Three Decimals)
(1) Have a look and fill it in.
Courseware demonstration ① Divide 1m into 10 parts, where 1 part is1dm; The average score is 100, where 1 is1cm; The average score is 1000, of which 1 is1mm.
(Show pictures) Students fill in the scores, which are expressed in decimals.
The Significance of Decimal Teaching Plan Part III Teaching Objectives:
1. According to the specific situation, grasp the approximate number of decimals by "rounding" and rewrite the larger number into a number with "10,000" or "100 million" as the unit.
2. In the process of learning the meaning and nature of decimals, cultivate interest in exploring knowledge.
3. Improve the ability to explore knowledge in cooperation.
Key points and difficulties:
Find the approximate number of decimals by rounding.
Teaching methods:
Independent inspiration, guidance and exploration
Teaching process:
First, review and introduce new lessons.
The teacher shows the review questions and asks the students to act them out.
372800 19000 725000000 844000000
Teachers and students * * * with revisions, click the "rounding method" to find the approximate number.
Teachers guide students to observe the information window.
Second, teach new lessons.
1, the teacher asked, "Why do two people have different readings when measuring the length of the same egg?" Give the students two minutes to think.
Some students may not see it, and the teacher guides them.
Teachers guide students to find the divisor according to the integer-rounding to solve the problem of finding the divisor by the decimal.
2. The teacher shows the numerical value "3.9423" for students to solve.
Some students may write "3.94".
Some may write "3.9".
Some may write "4".
3. Teachers guide students to compare and explore different results, discuss in groups, and then ask students to answer.
4, teachers and students * * * the same induction summary: use the "rounding" method to find the approximate number of decimals.
When the decimal place is reserved, only the number in its percentile is greater than 5 or less than 5. If it is greater than or equal to 5, proceed to 1 and discard the percentile and the digits after the percentile; If it is less than 5, the percentile and all numbers after it are directly discarded.
5. Teachers guide students to analyze and summarize: What should be paid attention to when calculating approximate decimals by rounding?
Some students may pay attention to the decimal point when answering;
Some students may answer be careful not to forget to bring;
Some students may answer, pay attention to rounding. ...
The teacher guides the students to sum up together.
Third, consolidate the use
The teacher asked the students to do the 1-3 problem by themselves, which consolidated the basic practice of finding the approximate value of decimals in various forms. (Students finish independently)
Fourth, inspiration and induction.
The teacher summed up the mathematics knowledge learned in this class and pointed out the difficulties. (Full communication among students)
Verb (abbreviation for verb) assigns homework.
Do exercises 4, 5 and 5 by yourself.
Blackboard design:
The world of eggs-the meaning and essence of decimals
3.9423≈3.94
≈3.9 Rounding ≈4
1754000 = 1754000 1754000 ≈ 175000.
The Meaning of Decimals Lesson 4 Teaching Content: The Meaning of Decimals
Teaching objective: 1. Let students understand the meaning of decimals.
2. Let students know that mathematics knowledge comes from real life and is used in real life.
3. Cultivate students' thinking ability through analysis, comparison and generalization. The initial infiltration of corresponding thinking and classified thinking.
4. Stimulate students to ask and answer questions boldly, and cultivate innovative consciousness.
Teaching emphasis: understanding the meaning of decimals
Teaching difficulty: understanding the meaning of three decimal places
Teaching preparation: ruler, courseware
Teaching process:
Talk before class: Classmates, have you visited the supermarket? What do you usually look at when choosing goods?
Look at the price tag first and draw out the decimal.
1. Before class, I learned that you all like to go to the supermarket. You bought food and clothes in the supermarket. So, do you buy school supplies? I found a stationery store, where stationery is good and cheap. Do you want to see it? After a while, let's take a closer look, choose a piece of writing paper that you like best or need most, and write it down, shall we?
2. Look at the courseware.
Tell me what you remember. What are these numbers? These prices are expressed in decimals. Can you express it in other ways? Have a try.
Tell your classmates what you think? If there is any difficulty in the group that can't be solved, tell the whole class later and we will study it together.
5. Report: (The teacher chooses the blackboard)
6. Just now, we studied so many decimals together and expressed them in fractions. Please observe carefully and read in a low voice. Did you find anything? (Thinking independently) Any ideas? Tell the students in the group quickly.
7. Report: Students find the relationship between decimals and fractions.
Second, solve practical problems.
1, we have a preliminary understanding of decimals. Where have you seen decimals except on the price tag? For example. Can you tell me what this means?
Step 2 measure. Grouping: (1) Measure the length of the objects around you. (2) expressed in decimals in meters. (3) Write the measurement results on the record sheet.
(mainly solve three decimal places)
Three. abstract
1. What else do you know about decimals? How did you know?
There is a lot of interesting knowledge about decimals. Do you want to get to know them better? How to learn this knowledge?
The meaning of decimals lesson 5 1. Reappear old knowledge and review it.
Courseware demonstration: Please classify the following figures. I believe you must be great.
0 7.523 6.8 69 10 1 1.25 384 0.00 1
The teacher answered the blackboard according to the students' mouths:
Integer: 0 69 10 1 384.
Decimal number: 7.523 6.81.25 0.0438+0.
The teacher said: In this class today, we will focus on reviewing the knowledge about decimals.
Second, group communication and self-grooming.
Think back, what did you learn about decimals? What is the connection between the corresponding integers? And please give an example.
Students discuss and communicate in groups.
Teachers should participate in students' knowledge arrangement, give necessary method guidance and guide students to learn from each other.
Third, the whole class exchanges and establishes a network of relationships.
1, in-class communication, arrange the blackboard according to the lens of the student communication teacher:
Integer decimal
meaning
(0 and natural number collectively ...) ←-→ (for a number ...)
finger
(... thousands, hundreds, ten pieces) ←-→ (one tenth, one percent ...)
Reading and writing method
(From high position ...) ←-→ (Integer part ...)
relative dimension
(First compare most significant bit ...) ↓————————→ (First compare the integer parts ...)
Operating rule
(a+b=b+a…… )← - →(a+b=b+a……)
Addition and subtraction
(The same number is aligned ...) ↓————————→ (Decimal alignment ...)
(Later written on the blackboard) The teacher summed it up.
2. The teacher said: The meaning of decimals is closely related to integers, so what is the connection between decimals and the addition and subtraction of integers?
① Courseware presentation: vertical calculation.
2.85+ 1.08 2.7+ 1.85 2 1.09—4.89 13—8.87
Independent calculation, in-class communication, let students talk about what to pay attention to when calculating decimal addition and subtraction. (Complete the blackboard writing above)
② Courseware presentation: First, carefully analyze the data characteristics of each topic, and then calculate independently. When communicating, talk about why it is so.
12.25+36+7.75 13.05+ 12.38—4.05
5.6—0.7 1—0.29 19.65—(3.98+6.65)
Fourth, practical application is consolidated and improved.
(1) Fill in the blanks
The number of 1, 7 0. 1, 3 0.00 1, 5 1 is (), which is pronounced as ().
2, a number minus 100 times is 0.8, and this number is ().
3. Arrange the following figures in order.
①0.58 0.85 0.085 0.058 0.8 0.805
()& lt()& lt()& lt()& lt()& lt( )
②0.9 1 m 1.0 m 1. 1 m 87 cm 0.69 m 9 decimeter.
()& gt()& gt()& gt()& gt()& gt( )
4. Keep four decimal places to 5.690 after three decimal places. The minimum decimal number is () and the maximum decimal number is ().
The decimal point of 5.96.4 is moved one place to the left and three places to the right, and the result is ().
(2) Distinguish right from wrong with a critical eye.
1, 4.60 and 4.6 are equal in size and accuracy. ( )
2. Decimals are smaller than integers. ( )
3. One percent of10 is one thousandth. ( )
4.0.9595 has three decimal places, which is 0.960. ( )
5. If the decimal point of 0.96 is removed, the original number will be enlarged by 1000 times. ( )
(3) choose one.
1, move 48.5 after the decimal point to the left of the highest digit, and this number will be reduced to its ().
① 1/ 10② 1/ 100③ 1/ 1000
2. Remove the "0" in the following figures and keep the same size ().
① 2430 ②2.043 ③2.430
3,6.5 is 6 () points.
① 5 ②50 ③30
4. The decimal number greater than 0.2 and less than 0.3 is ()
① Only 0.29 ② No ③ Countless.
5, a few tens, one tenth, and one thousandth are all 8, and the rest are all 0. This number is written as ()
① 18.808 ②80.808 ③8.088
(4) think with your head.
□0.□9. Fill in the numbers in□ to meet the following requirements.
(1) maximizes this number, which is ()
(2) Minimize this number, which is ()
(3) Make this number closest to 3 1, and this number is ().
Blackboard design:
The meaning and nature of decimals
Integer: 0 69 10 1 384.
Decimal number: 7.523 6.81.25 0.0438+0.
Reflection after class:
The Meaning of Decimals Lesson 6 teaching material analysis
This unit includes the meaning and reading and writing methods of decimals, the comparison of the nature and size of decimals, the change of decimal size caused by the movement of decimal position, the mutual rewriting of decimals and composite numbers, the approximate number of decimals, and the rewriting of larger numbers into numbers with units of "10,000" and "100 million".
The meaning of decimals is a key point in this unit. The textbook here expands the recognition range to three digits after the decimal point, and strengthens the connection between the decimal point and the fraction, so that students can clearly understand that the denominators after the decimal point are 10, 100, 10000 fraction ... and understand the counting unit of decimal places and the progress between units, so as to clearly understand why decimal places can be written as integers. The nature of decimals is also very important. Students know that adding 0 and removing 0 at the end of decimal does not change the size of decimal, which deepens their understanding of decimal. It is also the basis for calculating four decimal places. It can be used to simplify decimals, or to add 0 at the end of decimals or rewrite integers into decimals according to the needs of specific operations. The comparison of decimal size is also helpful to deepen students' understanding of decimal meaning. The nature of decimals has been involved in the comparison of decimal sizes, but it only shows when two decimals are equal. It is another property of decimal that the movement of decimal position causes the change of decimal size. It is the basis of decimal multiplication and division, and it is also the basis of learning how to rewrite decimal and composite numbers. The mutual rewriting of decimals and composite numbers and the divisor of decimals are widely used in practice, in which rewriting larger numbers into numbers with units of "10,000" and "100 million" is a comprehensive application of some knowledge learned in this unit.
Analysis of learning situation:
This part is based on the fourth grade students' mastery of four integer operations and their preliminary understanding of scores in the last semester. This part is the beginning for students to learn decimals systematically. Through this part of the study, students can further understand the meaning and nature of decimals and lay a good foundation for learning the four operations of decimals in the future. When students study the rewriting of decimals and composite numbers, they need to comprehensively use the knowledge they have learned before, such as the unit of measurement and the forward speed, the nature of decimals, the change of decimal size caused by decimal point movement, etc., so they are required to learn one by one. Finding the divisor of a number is easily confused with rewriting a number into "10 thousand" and "100 million", so we should pay attention to the difference.
Teaching requirements:
1. Let students understand the meaning of decimals, know the counting unit of decimals, read and write decimals, and compare the sizes of decimals.
2. Make students master the nature of decimal and the law of decimal size change caused by decimal position movement.
3. Let the students rewrite decimal and decimal composite.
4. Enable students to keep a certain number of decimal places by "rounding" as required, find out the approximate number of decimal places, and rewrite the larger number into decimals in tens of thousands or hundreds of millions.
Teaching emphasis: the meaning of decimal and the law of decimal size change caused by decimal point movement.
Teaching difficulty: mutual rewriting of decimal and composite.
The key to teaching is to correctly understand the meaning of decimals and the mutual rewriting of decimals and composite numbers.
The meaning of decimals The seventh lesson: Jiangsu Education Publishing House, Grade Three, Volume II, P 102 103.
Teaching objectives:
1, combined with the specific situation, so that students can understand the meaning of decimals, know, read and write decimals, and know the names of decimal parts.
2. Through observation, thinking, comparative analysis and comprehensive summary, let students actively participate, learn to discuss and communicate, and learn to cooperate with others.
3. Make students further understand the close relationship between mathematics and life, and cultivate students' habit of independent exploration, cooperation and communication. By understanding the generation and development process of decimals, students' interest in learning mathematics can be improved and their patriotic feelings can be enhanced.
Teaching aid preparation: multimedia courseware
Teaching process:
First, the situation import:
Xiaoming has moved to a new home. He needs a new desk. His mother asked Xiao Ming to go to the store to choose it himself, but asked him to record the length and width of the table he chose. After receiving the task, Xiaoming invited his good friend Xiaohong to come to the store. Let's take a look at the table they chose. (Courseware demonstration)
(Comments: The class creates a situation suitable for students' life and learning content, so that students can actively learn mathematics in vivid and concrete situations and feel that there is mathematics everywhere in life. )
Second, the exploration of new knowledge:
1, identifying decimals whose integer part is 0.
(1) What did you learn from the information of 5 decimeters long and 4 decimeters wide?
② The requirement of * * is in meters. How many meters are 5 decimetres and 4 decimetres? Think about what you have learned before.
(3) What fraction of decimeter is decimeter? How many decimetres is a decimetre?
With the students' answers, the teacher pointed out: 5 decimeters is to divide 1 meter into 10 shares on average, and 5 decimeters is one of them, which can be expressed by the score of 5/ 10 meter.
(Comment: It is in line with students' cognitive rules to take students' existing knowledge as the starting point of new knowledge. At the same time, teachers guide students to acquire knowledge by reading information, learning and analyzing information, and skillfully realize the transfer from life problems to mathematics problems. )
The teacher pointed out with the students' answers that the length of 5 decimeters is to divide 1 meter into 10, and 5 decimeters is one of them, which can be expressed as 5/ 10 meter.
Besides 5/ 10 meter, it can also be expressed by 0.5 meter.
Please look carefully. How to write 0.5m? Reading: 0.5
What's the decimeter score? How to express it in decimal? (The courseware demonstration is the same as above)
⑤7 decimeters? After the students answer, think about doing the first question. After the answer, communicate in the group: Why do you want to fill in this way?
⑥ Student Report: Courseware Demonstration
1 decimeter 3 decimeter 7 decimeter 9 decimeter
1/ 10m 3/ 10m 7/ 10m 9/ 10m
0. 1.3m 0.7m 0.9m
Observe carefully: what do you find that a few tenths of a score can be written as a decimal? What does this mean?
⑦ Hands-on operation:
Fold out 2/ 10 from a rectangular piece of paper, and then express it in decimal.
Fold 0.6 out of a rectangular piece of paper.
Summary: A few tenths can be written as decimals, and a few tenths represent ten times.
Writing on the blackboard: the meaning, reading and writing of decimals
Summary: Decimals are produced in the needs of people's actual measurement and calculation, and are widely used in our real life. Liu Hui, an ancient mathematician in China, began to use decimals more than 700 years ago. (Courseware introduces ancient mathematician Liu Hui)
(Comment: Teachers should infiltrate moral education in mathematics teaching in time to stimulate students' national pride and enhance students' patriotic feelings. )
Tell me where else you have seen decimals.
2. Be aware that the integer part is not a decimal of 0.
Xiao Ming and Xiao Hong walked around the shop after choosing the table. They saw the ballpoint pen 1 Yuan 2 and the notebook 3 yuan 5. Can you show me the decimal number of ballpoint pens and notebooks?
① Students explore independently, and then cooperate and communicate in groups.
② Students report and complete the blackboard writing.
1 yuan 2 jiao can also be written as 1.2 yuan is pronounced as: 1.2.
3 yuan's Pentagon can also be written as 3.5 yuan, which reads: 3.5.
Summary: A few yuan and a few cents are divided into two parts, and a few yuan and a few cents. First, express a few cents into a few dollars, and then add them up to a few dollars.
③ Observing decimals: What are the characteristics of these decimals?
The point in the middle of the decimal is called the decimal point, which divides the decimal into two parts, the integer part on the left and the decimal part on the right.
1, 2,3, which we learned before, are natural numbers, and 0 is also a natural number. They are all integers. Today's 0.5, 0.4, 1.2 and 3.5 are all decimals.
4 Write a few decimals at will and read them in the group.
When the class communicates, say the integer part. What is the score?
(Comment: How to carry out inquiry learning in the classroom is a problem that math teachers are exploring at present. This section of teaching has done a good show in this respect. Students make full use of independent inquiry, hands-on practice and cooperative communication to carry out multi-angle and multi-level inquiry activities. Students' communication and teachers' timely guidance complement each other, pushing the exploration activities deeper and deeper. )
Third, the application of reflection:
1, Xiaoming and Xiaohong also see that there is a lot of food in the shop. Think about doing the second question. )
Can you show the price of these foods in RMB?
2. They also saw some commodities express their prices in this way. Think about doing the fourth question. )
Read out the prices of these goods first, and then say how many yuan and how many cents.
Xiaoming and Xiaohong not only chose their favorite desks in the shop, but also learned a math knowledge. Have you learned?
After thinking, do the fifth question.
(Comments: The design of exercises always allows students to solve problems in life situations, which not only improves students' interest in continuing their studies, but also enables students to truly appreciate the close relationship between mathematics and life. )
Fourth, after-school development:
Decimals are everywhere in our life and production. Students should learn to observe life from a mathematical perspective and solve practical problems in life with mathematical knowledge.
[General Comment: This lesson starts from students' real life, and tries to select examples around students, so that life materials can run through the whole teaching. Pay attention to the close connection between mathematics and students' life, follow the principle that mathematics comes from life, and realize the application value of mathematics. Specifically, it has the following characteristics:
1, create a life situation and make math problems come alive.
In this class, the teacher created the life situation of Xiaoming and Xiaohong going shopping from the beginning, which runs through the whole teaching process. Let students feel that what they have learned is no longer simple and boring mathematics, but very interesting and intimate. They feel that mathematics is everywhere in life, and mathematics is around them. They are driven by a strong living atmosphere and are interested in learning new lessons.
2, independent inquiry, cooperation and exchange, so that students can experience the process of knowledge formation.
Mathematics knowledge, ideas and methods must be understood, understood and developed by students in practical activities, rather than simply obtained through teachers' explanations. According to this idea, teachers should proceed from the students' cognitive laws and knowledge structure in teaching, and let students actively construct their own cognitive structure from intuition to abstraction through purposeful observation, operation, communication and discussion.
3. Organic infiltration of ideological and moral education to cultivate students' patriotic feelings.
Cultivating students' emotional attitude and values is one of the important teaching goals of every teacher. This course introduces Liu Hui, an ancient mathematician in China, on the basis of fully excavating the teaching content and developing students' ability, so that students can understand the long and splendid culture of China, enhance their patriotic feelings and establish their belief in building the motherland.
In a word, the teaching of this course pays attention to the concept of students' development and the cultivation of students' independent inquiry, innovative spirit and practical ability. By creating situations, combining mathematics knowledge with real life, students can think, experience and feel in operation, communication and inquiry, learn mathematics in practice, experience the fun of learning mathematics in learning, and develop their emotions, attitudes and values while acquiring knowledge and forming skills.