Three teaching plans of "the nature of decimals" in the second volume of mathematics in the fourth grade of primary school

# Lesson Plan # Introduction Add or delete 0 at the end of the integer, the size of the integer changes greatly, but add or delete 0 at the end of the decimal, and the size of the decimal remains the same. I have not prepared the following lesson plan, I hope it will help you!

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Teaching content:

Page 38 and 39 of the textbook in the second volume of grade four and the exercises 10 1, 2, 3 and 4.

Teaching purpose:

1. Guide students to understand and master the nature of decimals, and simplify and rewrite decimals by using the nature of decimals.

2. Cultivate students' hands-on operation ability and the ability to observe, compare, abstract and summarize.

3. Cultivate students' preliminary mathematical consciousness and thoughts, make students realize the internal relationship of mathematical knowledge, and infiltrate the view that things can be transformed into each other under certain circumstances.

Teaching focus:

Let students understand and master the nature of decimals.

Teaching difficulties:

Can apply the properties of decimals to solve practical problems.

Teaching steps:

First, create situations and introduce new lessons.

In summer, students all like to eat cold drinks. The teacher learned that the price of an ice cream in the shop on the left of the school gate is 2.5 yuan, and the price on the right is 2.5 yuan. Which one will you choose when you buy it? Why?

Why is there a zero price after 2.5 yuan? How many zeros can you add? We will learn this knowledge in this class.

Second, put forward topics and goals.

1. Know and master the properties of decimals, and can simplify and rewrite decimals by using the properties of decimals.

2. Cultivate hands-on operation ability and the ability to observe, compare, abstract and summarize.

3. Cultivate the preliminary mathematical consciousness and thought, and know the internal relations of mathematical knowledge.

Third, try to teach yourself and explore new knowledge.

1. Show test questions

Are the numbers (1) 1, 10 and 100 equal? Can you find a way to make them equal?

(2) Can 1 decimeter,10cm and100mm be changed to "meter"?

(3) Has the actual length changed after rewriting in meters? Explain what?

(4) The equation "0.1m = 0.10m = 0.100m" is viewed from left to right. What is the last change of decimal? What's the change in decimal size? Look from right to left? What pattern did you find?

2. Students try to practice and discuss after learning 38 pages of textbooks by themselves. (After 5 minutes, the whole class will communicate).

3. Guide and explain according to the self-study situation.

Fourth, expand the practice and verify the conclusion.

In order to verify our conclusion, let's do another experiment.

1. Show and do: compare the size of 0.30 and 0.3.

What do you think of the size of these two numbers? (Let the students guess by applying the conclusion first)

Think about how you compare these two numbers. Give students time to think independently and discuss cooperation in groups. The more ways you think, the better.

3. Color two squares of the same size and compare them.

(1) How many parts does the left picture divide the square of 1? How to express the shaded part in fractions? How to express it in decimal?

(2) How many shares does the picture on the right divide the same square equally? How to express the shaded part in fractions? How to express it in decimal?

(3) The decimal range is 0.3 to 0.30. What changes have you seen? What hasn't changed? What did you find out from it? (The average number of copies has changed, that is, the counting unit of decimals has changed, but the size of the shaded part has not changed, and the result is 0.3 = 0.30. )

Summary: Add "0" or remove "0" at the end of the decimal, and the size of the decimal remains unchanged. This is the so-called decimal nature.

Excessive: If we encounter a "0" after the decimal point, we can generally remove the "0" at the end and simplify the decimal point.

Fifth, apply new knowledge and try to practice.

(1) Example 3: Simplify 0.70 and 105.0900.

Example 4: Rewrite 0.2, 4.08 and 3 into decimals with three decimal places without changing the size of numbers.

(2) Students discuss and communicate after teaching materials by themselves, and try to practice.

(3) Guided inquiry: Which "0" can be removed and which "0" cannot be removed?

Why can't the "0" before "9" in 105.0900 be removed?

Is there no decimal point after "3"? Why?

(4) Discussion at the same table: What should we pay attention to when applying the nature of decimals?

Sixth, consolidate new knowledge and conduct classroom tests.

1. Which "0" in the following figures can be removed and which "0" cannot be removed?

3.90m 0.30 yuan 500m 1.80 yuan 0.70m 0.04 yuan 600kg 20.20m.

2. If "0" is added at the end of the following numbers, which numbers have the same size and which numbers have changed in size?

3.4 18 0.06 700 3.0 908 104.03 150 10.0 1 42.00

3. Simplify the following decimals.

0.40 1.850 2.900 0.080 12.000

4. Rewrite the following decimals into decimals with three decimal places without changing the number size.

0.9 30.04 5.4 8. 18 14

Judge.

5.00 yuan = 5 yuan () 7 yuan = 0.7 yuan () 8m = 8.00m ().

2.04 tons = 2.4 tons () 4.5 kilograms = 4.500 kilograms () 0.60 liters = 0.6 liters ()

6. In yuan, write the following price to two decimal places.

3 yuan, 2.6 jiao, 8 yuan 1 yuan and 3 points.

Seven, class summary.

This lesson learned the properties of decimals. Add "0" or remove "0" at the end of the decimal, and the size of the decimal remains the same. When applying the properties of decimals, we should pay attention not to remove the zero in the middle of decimals.

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Teaching objectives:

1, knowledge goal: guide students to understand the essence of decimals; Can use the nature of decimal to simplify decimal and rewrite decimal correctly.

2. Ability goal: to stimulate students' active spirit of inquiry and cultivate their ability of inductive analysis.

3. Emotional goal: to cultivate students' love for learning mathematics.

Teaching focus:

Understand that adding "0" or removing "0" after the decimal point will keep the size of the decimal point unchanged. And correctly use this property to solve related problems.

Teaching difficulties

Master where to add "0" to the "0" in the decimal part, and the size of the decimal remains the same.

Teaching aid preparation: learning paper "little magic" paper card multimedia courseware

Class hours: 1 class hour

Teaching process:

First, scene transformation (magic)

1. Teacher: Students, this is the first time to teach you. Out of courtesy, I'll show you a magic trick-the change of numbers. See, this is the number 1? Later, you will all whisper: 1, 2, 3, big, and the teacher can make this number bigger. Believe it or not?

Health: 1, 2, 3, big.

Teacher: The ratio of 1 to 10, 10, 1 has been expanded by 10 times. ...

2. The teacher also has a number 0. 1. Let's try again.

Causing conflicts among students: Is it getting bigger?

(Intention: It is to stimulate students' interest in learning and ignite the spark of their desire for knowledge through boring mathematics knowledge through games that primary school students like to listen to music, so as to enter a new learning state and gather motivation for actively exploring new knowledge. )

In this lesson, we will learn the influence of "0" at the end of decimal system on decimal size. This is what we are going to learn today-the nature of decimals.

Second, explore new knowledge.

(1) Teaching examples 1

1. Teacher: 0. 1 m, 0. 10 m, 0. 100 m, will it be equal?

Teacher: Please take out your test paper and finish the first question.

Report: Ask students to perform on stage. Fill in the blanks, and it is found that this is 0.1m = 0.10m = 0.100m.

Tell the students how you found 0. 1 m, 0. 10 m, 0. 100 m in teaching.

(0. 1 m is a decimal place, and its counting unit is110, with110, that is, 0.1m =/kloc-0. So 0. 1 m = 1 decimeter.

0.10m is a two-digit decimal, and its counting unit is1100, with10100, which means 0.10m =/kloc. So 0. 10 m = 10 cm.

0.1000 m is a three-digit decimal, and its counting unit is11000, with 15438+0/ 1000 m = So 0. 100m = 100mm. )

Because 1 decimeter =10cm =100mm, 0. 1 m = 0.10m = 0.100m.

Teacher: 0.1m = 0.10m = 0.100m (blackboard writing) These three lengths are the same, all in meters, so we can abstract the number as 0.1= 0.10.

(Design intention: In this way, according to the meaning of decimals, students will take the initiative to study the problem from "0.l m, 0.10m, 0.100m". In the process of solving problems, students have exercised their ability to use existing knowledge to solve new problems and cultivated their awareness of using mathematical knowledge.

Look at this group of decimals carefully. What did you find?

Health: Add "0" after the decimal point, and the size of the decimal point remains the same.

Teacher: The students' eyes are really sharp. Add "0" at the end of the decimal, and the size of the decimal remains the same. I have a question now, do other decimals have such characteristics?

Teacher: Now please open the study paper and come up with a set of decimals, which are represented by the grid diagram.

Students operate, communicate and report.

Courseware display.

(Teachers should strengthen guidance in study and research)

Teacher: Now, please observe the decimals in the above questions. Can you name several groups of decimals similar to them?

The student said.

Teacher: You can name so many groups. You must have found some patterns, right? (Communications, reports)

Summary: Add "0" or remove "0" at the end of the decimal, and the size of the decimal remains unchanged.

(Design intention: This kind of teaching transforms the static knowledge conclusion into a dynamic process of seeking knowledge, so that students can truly become the masters of learning and have a deep understanding and a solid memory of what they have learned. At the same time, it also cultivates students' ability to summarize the essential attributes of things. )

3. Get in touch with life and reproduce new knowledge: Some students saw the price tag of goods in the shopping mall, for example, this writing not only did not change the size of the decimal point, but also let customers know clearly how much it was.

(B) the application nature of the decimal system

1. Teaching Example 2

Teacher: Now that we know the nature of decimals, we can apply the nature of decimals and rewrite decimals as needed.

Computer demonstration: simplify the following decimals. 0.70= 105.0900=

Teach 0.70=0.7

Q: ① How did you simplify it? According to the nature of decimal, decimal can be simplified by removing the "0" at the end of decimal.

② Are 0.70 and 0.7 the same size, but the same meaning?

(Different, 0.70 means 701100, and 0.7 means 7110).

Teaching 105.0900= 105.09

Q: Can other "0" in the decimal be removed? Why? No, the size has changed. The teacher should emphasize the end)

2. Teaching Example 3

Computer demonstration: Write the following figures into three decimal places without changing the size of the figures.

0.2 = 4.08 = 3 =

Teacher: How did you rewrite it to three decimal places? (According to the nature of decimals, adding "0" at the end of decimals will keep the size of decimals unchanged)

Teacher: How to rewrite it to three decimal places? Is it okay if the decimal point doesn't count?

Note: a, add "0" after the decimal point.

B. When the number is an integer, add "0" after the decimal point in the lower right corner of the integer digit.

Teacher: What should I pay attention to when applying decimal properties? (Decimal, End)

Third, consolidate the practice.

Do it on page 59 of the textbook. 2. Answer page 59 by train.

Q: How did you simplify and rewrite these figures?

Fourth, the whole class

1. What did you learn in this class?

Add "0" or remove "0" at the end of the decimal, and the size of the decimal remains the same.

2. How do we explore the essence of decimals?

Adding or removing 0 at the end of an integer will greatly change the size of the integer, while adding or removing 0 at the end of a decimal will not change the size of the decimal. But by adding or removing 0 after the decimal point, we find that there are many friends of the same size for a decimal point. 0 is such a wonderful number. In fact, there are many wonderful phenomena in the kingdom of mathematics, waiting for us to explore and discover.

Words on the blackboard: the essence of decimals

The Influence of "0" at the End of Decimal on Decimal Size

Add "0" or remove "0" at the end of the decimal, and the size of the decimal remains the same.

0. 1m = 0. 10m = 0. 100m。

0. 1=0. 10=0. 100

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Teaching content:

The second volume of the fourth grade mathematics textbook published by People's Education Press has 58 pages of examples 1 and doing, 59 pages of examples 2, 3 and doing, and 64 pages of exercises 10.

1. Let students understand what is the essence of decimals. 1, 2, 3 questions.

Teaching objectives:

Learn to use the nature of decimals to simplify or rewrite some decimals;

2. Cultivate students' ability to ask and solve problems independently, as well as the spirit of cooperation, practical ability and innovative consciousness;

3. Stimulate students' interest in mathematics and guide them to understand the relationship between mathematics and life.

Teaching focus:

Master the meaning of decimal nature.

Teaching difficulties:

The process of decimal property induction.

Teaching process:

First, import the theme.

1. There are two stationery stores at the school gate. The price of the triangle cover on the left is 2.8 yuan, and the price of the triangle cover on the right is 2.80 yuan. Students, what do you think of their prices? How do you compare?

2. Why do you add a zero after 2.8 yuan? What's going on here? We will learn this knowledge in this class. (blackboard writing: the essence of decimals)

Second, the nature of exploration

1, teaching example 1.

(1) Project an example of 1, let the students look at the questions and make clear the requirements.

(2) Inspire students to mark the length of 0. 1 m, 0. 10 m, 0. 100 m on the meter scale according to the meaning of decimals (the teacher projects the meter scale map) and express them with integers. If students have difficulties, the teacher takes 0. 1 meter as an example to demonstrate:

0. 1 m means 110 m, i.e.110 m, i.e.1decimeter, as shown in the figure:

About 0. 10 meter, 0. 100 meter, let the students be independent or finish the discussion.

(3) Feedback the students' completion, and show the formed consensus through projection:

0. 10 means 10/ 100 m, that is, 10 m, that is, 10 cm, as shown in the figure:

0. 100 m means 100/ 1000 m, that is, 100 m, that is, 100 m, as shown in the figure:

(4) The teacher affirmed the students' learning activities, and overlapped the projections of three meters scale maps twice, so that students could observe and ask questions: What do you think is the relationship between the size of 0. 1 m, 0. 10 m and 0. 100 m? Please tell the truth. (Organize students to discuss in groups)

Teacher's blackboard: Because 1 decimeter =10cm =100mm, it is 0. 1 m = 0.10m.

(5) Guide students to observe the equation 0.1m = 0.10m = 0.100m Q: What do you find by comparing these three decimal places? Inspire students to observe from left to right, and then from right to left, and draw a preliminary conclusion: add 0 or remove 0 at the end of the decimal, and the size of the decimal will remain unchanged. (blackboard writing)

2. Verify the nature

(1) Students complete the 58-page "Do it" by themselves.

(2) Ask students to compare the size of 0.3 and 0.30 from the visual diagram.

(3) What does the result of 0.3 = 0.30 mean?

Third, the nature of application.

1, teaching example 2

(1) The teacher explained to the students that the decimal point can be simplified by taking 0.70=0.7 and removing the "0" after the decimal point. (blackboard writing: simplified)

(2) Students completed 105.0900=

(3) Can other zeros in105.0900 be removed? Why?

(4) In classroom communication and emphasizing the nature of decimals, we say "0 at the end of decimals".

(5) Complete 59 pages and do the problem 1.

A, students do it themselves.

B, the whole class corrects the answers.

2, teaching example 3:

(1) Teacher's Note: Using the nature of decimals, you can "rewrite a number into decimals with specified decimal places" as needed. ("Rewrite" on the blackboard)

(2) Students do it themselves.

(3) What is the basis for everyone to do this?

(4) Explain that any integer can be regarded as a decimal with a decimal part of 0. Don't forget to put the decimal point in the lower right corner of the unit when rewriting an integer to a decimal point with a specified number of decimal places.

(5) Finish page 59 and do the second question.

A, students do it themselves.

B, the whole class corrects the answers.

3. What should I pay attention to when applying the nature of decimals?

(1) Discuss the following three questions:

A, 0.70, MINUS 0, the size of the decimal remains the same?

B, 4.08 What happens when you remove 0?

C, 0.3 1 Can I add 0 at the end?

(2) Reading the nature of decimals in class, emphasizing "adding 0 or removing 0 at the end of decimals".

Fourth, reading questions.

Students read the textbook on page 58.59, ask questions and communicate with each other to solve problems.

Verb (abbreviation for verb) consolidation exercise

1. Which of the following statements is true? If not, please give a counterexample.

(1) Add or delete 0 after the decimal point, and the size of the decimal point remains unchanged.

(2) Add 0 or remove 0 at the end of the decimal, and the size of the decimal remains unchanged.

(3) Add 0 or remove 0 at the end of a number, and the size of this number remains unchanged.

After practice, ask: Which words do you think are the most important in the expression of decimal nature? (The teacher put bullets under "decimal" and "mantissa")

2. Do questions 1, 2, 3 on page 64.

Question 1 Please tell me which positions can't be removed after practice. 0 in (1) integer cannot be deleted anywhere; (2) Decimal non-final 0 cannot be deleted)

Sixth, the class summary

1. What have you gained from this course?

2. Evaluate yourself or a classmate's learning enthusiasm in this class.