Teaching objectives of the teaching plan (1) of the second volume of fourth grade mathematics: the meaning of decimals and reading and writing methods;
1, understand how decimals are produced, and understand and master the meaning of decimals.
2. Make clear the relationship between decimals and fractions, and master the counting unit of decimals and the forward speed between them.
3. Experience the discovery and understanding of decimals, perceive the close relationship between knowledge and life, experience the learning methods of inquiry discovery and transfer reasoning, and cultivate the learning habits of hands-on practice and cooperative inquiry.
Teaching emphases and difficulties:
Key points: understand and master the meaning of decimals, the counting units of decimals, and the progress between them.
Difficulty: Understand the counting units of decimals and the forward speed between them.
Teaching tools:
courseware
Teaching process:
First, check the import.
The teacher showed the courseware and asked, Let's meet some old friends first. Do you still know them? Who will read it?
It refers to a student who tries to read.
Teacher: Read together.
Read all the students.
Teacher: Think about it. How much should I put in brackets?
Answer by roll call.
Show me the picture in the textbook.
Teacher: What are their measurement results?
Health: 1 m 1 decimeter, 1 decimeter.
Teacher: If only the meter is used as the unit, how should it be expressed?
Health: 1, 1 m, 1, 2 m (blackboard writing)
Teacher: Where can I see decimals in my life? Look at some pictures. (Courseware shows decimals in life)
Teacher: We call a decimal with numbers after the decimal point a one-digit decimal. Are there any decimals?
Two digits after the decimal point are called two decimal places. Can you find them?
Who can tell the decimal of three digits?
Teacher: When measuring and calculating, it is often impossible to get accurate integer results, so it is often expressed in decimals. We will continue to learn decimals in this class. (blackboard title: the meaning of decimals)
Second, explore new knowledge.
1, explore the meaning of one decimal place.
The teacher showed the courseware: divide one meter into ten parts on average. How much is a part here?
Health: One decimetre.
Teacher: How many meters are expressed in fractions? Health: One tenth of a meter.
Teacher: How many meters is the decimal system?
Health: 0. 1 m
Teacher: Divide one meter into 10, and 1 0 is 1 decimeter. Expressed as a fraction, it is one tenth of a meter, and the decimal is 0, 1 meter. There are still two brackets to fill in. Let's finish them by ourselves, shall we?
After the students have finished speaking, the teacher will call the roll to answer, and let the students express their ideas and evaluate them collectively.
Teacher: Look at these fractions and decimals. Do you have anything to say?
If students have difficulties, the teacher will guide them: What is the denominator of these scores? How many decimal places are there?
The fraction whose denominator is 10 can be expressed by one decimal place. (Teacher writes on the blackboard)
Teacher: Do you understand? Test you and complete the exercise of homework paper consolidation 1
Students complete, answer by name and correct collectively.
2. Explore the meaning of two decimal places.
Teacher: Just now we divided the rice into 10. What would it look like if it was divided into 100 parts on average? Take a look. (Courseware demonstration)
Teacher: How much is one?
Health: 1 cm
Teacher: How many meters are expressed in fractions?
Health: One hundredth of a meter.
Teacher: What about the decimal system?
Health: 0.0 1 m
Teacher: That's very clever. Then the following brackets are left to you to complete independently.
Student completion, teacher name, collective evaluation.
Teacher: Let's look at these fractions and decimals again. What did you find?
Students communicate with each other and come to the conclusion that the score with denominator of 100 can be expressed with two decimal places. (Teacher writes on the blackboard)
Teacher: Have you learned? I have to test you. Please complete consolidation exercise 2 on the homework sheet.
Students finish independently, answer by name and revise collectively.
3. Explore the meaning of three decimal places.
Teacher: How does it feel to divide one meter into 1000 parts? What will you find?
Now give this task to you and your deskmate, exchange and discuss, and complete the third inquiry.
Students cooperate and exchange, and teachers patrol.
Students finish, report their grades and correct them collectively.
Teacher: Can you draw a conclusion by observing the scores and decimals here?
Student: Fractions with denominator of 1000 can be expressed in three decimal places. (Teacher writes on the blackboard)
4. Infer and summarize the meaning of decimals
Teacher: imagine: divide a meter into 10 thousand parts on average. How can one part be expressed by a fraction? What about decimals? What if the average share is100000?
Teacher: Can we sum up what we just found into a concise sentence?
Students communicate with each other, and the teacher guides them to say that the denominator is 10, 100, 1000,, and the score can be expressed in decimals. (Teacher writes on the blackboard)
Teacher: Now apply what we have learned. Please complete the assignment paper "Apply feelings and consolidate meaning".
Finish, answer by name, and modify.
5. Know the decimal counting unit and rate.
Show courseware: think about it, how many zeros are there in 0 and 3, 1?
Health: 0 and 3 have three zeros, 1.
Teacher: How many zeros are there in 0 and 06, 0 1? How many of 0 and 007 are 0,001?
The students answered in turn,
Teacher: What are the scores of 0, 1, 0, 0 1 and 0,001respectively?
Health: one tenth, one percent, one thousandth.
Teacher: The counting unit of decimals is one tenth, one hundredth, one thousandth,,,, written as 0, 1, 0, 0 1, 00 1,,,, respectively.
Teacher: Think again: How many percent are there in one tenth? How many thousandths are there in one percent?
The students answered.
Teacher: So what is the rate of the series of two adjacent counting units of decimal?
Health: Yes 10.
Third, comprehensive application, expansion and upgrading.
Students independently complete the "comprehensive application" on the homework paper.
Question 1: Answer by name and correct collectively.
Question 2: Answer by name and say what you think.
Fourth, broaden your horizons.
Courseware shows the textbook "Do you know? Read by name.
Verb (abbreviation of verb) course summary
What did you learn from this course?
The teaching plan of the second volume of the fourth grade mathematics "the meaning of decimals and reading and writing methods" (2) teaching objectives;
Let the students understand the meaning of decimals, know the counting unit of decimals, read and write decimals and compare the sizes of decimals.
Teaching process:
1, the generation and significance of decimals
(1) theme map. This paper briefly introduces the process of "decimal generation".
(2) Example 1.
① Choose the meter ruler as an intuitive teaching aid to teach the meaning of decimals, and take the length unit as an example to illustrate that decimals are actually another representation of decimals.
The arrangement is divided into three levels: first, the decimeter number is rewritten as the meter number, and the decimal number is expressed by one decimal place; Then rewrite the number of centimeters into the number of meters, indicating that the percentage is expressed by two decimal places; Then rewrite the number of millimeters into the number of meters, indicating that several thousandths are expressed with three decimal places. The content and description of level 3 * * * are the same. If the number of lower units is rewritten as the number of higher units, it can be expressed by fractions with denominators of 10, 100, 1000, and further expressed by decimals.
③ On the basis of the above, summarize the meaning of decimals abstractly. Let the students understand that fractions with denominators of 10, 100, 1000 can be expressed in decimals. Finally, the textbook explains the counting units of decimals, and the progress rate between units is filled in by students themselves.
2. Decimal reading and writing.
Arrangement of (1) decimal digit sequence table.
It consists of three specific decimals with different digits, indicating that decimals consist of integer parts, decimal points and decimal parts; Then explain the meaning of each number in the decimal system.
On this basis, the decimal order table is sorted out. In the form of a table, the numerical names of decimals are intuitively corresponding to the corresponding counting units, and at the same time, the numerical relationship between the integer part and the decimal part is expressed, so that students can be familiar with the position of each decimal place and the number represented.
Complete the number sequence table.
(2) Example 2, Decimal reading teaching.
There are two ways to read decimals, one is direct reading, that is, the integer part is read as an integer, and the decimal part should read the numbers on each bit in sequence. This method is easy to learn and write decimals. Another reading method is reading according to the meaning of fractions, which is consistent with fractional fractions and helps to understand the meaning of decimals. Considering that students know little about fractions at present, textbooks only teach direct reading of decimals.
Note: ① The integer part is a decimal of 0, and the integer part is read as "zero".
② If there are several zeros in the decimal part, read several zeros. This can be understood and consolidated by creating different forms of exercises.