The fifth grade mathematics second volume "the interaction between fractions and decimals" teaching plan one teaching goal
(1) Make students further master the reciprocal method of fractions and decimals, and master the reciprocal skillfully.
(2) Be able to skillfully compare the size of fractions and decimals.
Teaching emphases and difficulties
Emphasis and difficulty: reciprocal method of fractions and decimals; Compare fractions and decimals.
Preparation of teaching AIDS and learning tools and teaching process
Reserve bill
First, knowledge arrangement and basic exercises
1, talk about the reciprocal method of fractions and decimals.
2. Talk about the law that a simplest fraction becomes a finite decimal.
3. Decimal following components.
0.0060.240.875 1.084.0258. 19
After students practice independently, give feedback and correct their mistakes.
4. First judge whether the following scores can be converted into finite decimals, and then convert these scores into decimals. (If it cannot be converted into a finite decimal, keep three decimal places)
13/54/117/825/67/25 and 4/ 15.
5/ 123/203 and14/913/361/4018/125.
Students practice independently, give feedback and correct mistakes.
Second, comprehensive exercises.
1, how to compare the size of 5/7 and 9/2 1, do exercise 2 in groups, and then report the exchange.
Teachers and students summarize the blackboard writing as follows:
(1) Compared with the general score: 5/7 = 5× 3/7× 3 =15/21because15 >; 9/2 1, so 5/7 >: 9/2 1.
(2) Compared with divisor: 9/21= 9 ÷ 3/21÷ 3 = 3/7 because of 5/7 >; 3/7, so 5/7 >; 9/2 1。
(3) Because 5/7 is more than half of 1 and 9/2 1 is less than half of 1, 5/7 >; 9/2 1。
2. Compare the scores of the following groups.
5/ 12 and 1/24 1 and 5/6 and 1 and 2/9 1 and 3/8,1and 7//kloc-0.
Students practice independently, then ask four students to make slides, and then comment collectively.
3. In the textbook, page 1 14, question 17, students think independently and then comment collectively. The teacher pointed out that the more time you spend, the slower you do it.
4. The textbook question 1 14. Ask the students to discuss collectively. After reading, talk about the way to solve the problem.
Students determine the steps to solve the problem: First, how much do protein, starch and fat account for in the total weight?
teaching process
Reserve bill
Then compare these scores with those of the university.
5. Class assignments.
Textbook 1 13 Page 15 (4)(5)(6), 16.
Third, discuss and think.
1, show the thinking questions.
2. Guide students to analyze.
3. Draw a conclusion from this.
Fourth, after-school homework "exercise book"
Give priority to students' practice and teach students the method of thinking. Cultivate students' logical reasoning ability and develop their thinking by thinking.
Teaching plan 2 1 of the interaction between fractions and decimals in the second volume of fifth grade mathematics, paving the way for exercises.
1. Can you classify the following figures?
0.9 0.82 0.3 0.52 1
2. Name the students, and what is the counting unit of the above numbers?
The teacher's summary after the students answer; The unit for calculating one decimal place is one tenth, and the unit for calculating two decimal places is one hundredth.
3. Compare the sizes of the following numbers.
0. 16 and 0.26 0.3 and 0.24 4/5 and 2/5 2/5 and 2/ 10.
The students replied how to compare.
Second, explore new knowledge.
1. Teaching example 9.
(1) Give an example of 9. Observe carefully and tell me what mathematical information is provided on the diagram.
(2) Group discussion: How to compare the dimensions of 0.5 m and 3/4 m?
Students discuss and report, and the teacher writes on the blackboard appropriately: 3/4=3÷4=0.75.
Teacher: Students, what is the basis for us to convert fractions into decimals in this way? How to convert fractions into decimals?
2. Try it independently.
(1) Students try to make fractions into decimals in the way they have just learned, at the same time, say the names of the boards and act them out, and then * * * comment on each other.
(2) Summary: According to the relationship between fractions and division, we can divide fractions into decimals by numerator. Pay attention to keep a certain number of decimal places according to the requirements of the topic when calculating.
3. Learning example 10.
Teacher: Students, how can we divide decimals into numbers?
(1) Speak: Observe these decimals carefully. How many decimal places do they have? Think about it. What do they mean? How to divide them into numbers?
(2) Students independently try to decompose decimals into parts.
(3) Teacher: Who will tell you about the decimal method of component number?
Third, consolidate the practice.
1. Complete the "Exercise" independently.
Students do it independently. Name the students and talk about how to compare the numbers in each group in the question.
2. Complete Exercise 9, Question 7.
Fill in the blanks in the book and then ask the students to answer.
3. Exercise 9, Question 10.
4. Exercise 9, Question 1 1.
Remind students to understand "Who can do it faster?" The practical significance expressed.
5. think about the problem.
Students finish independently first, and then the whole class reports and exchanges.
Fourth, the class summary
1. What have you gained from this course?
2. Are there any questions you don't understand?
Teaching Plan III of Reciprocal Fractions and Decimals in the Second Volume of Grade Five Mathematics [Teaching Objectives]
1. Make students master the method of decimal number of components and fractions, and exchange fractions and decimals correctly.
2. Cultivate students' abilities of observation, analogy, analysis, synthesis and abstraction.
3. Cultivate students' thinking quality of being good at observation, thinking and generalization, and infiltrate the transformed thoughts.
teaching process
This lesson is divided into four parts.
1.
(1) oral calculation.
(2) Use decimals and fractions to represent the colored parts in the figure below.
When reviewing, talk about the meaning of decimals in combination with this question.
(3) One tenth of 9 () in 0.9 means one tenth of ().
(4) There are seven tenths () in 0.07, which means ten tenths ().
(5) In 0.0 13, there is 13 () point, which means () point.
(6)4.27 means () and ().
[Revision: (3) Ten tenths, nine tenths; (4) 100% and 7%; (5) Thirteen thousandths; (6) Four percent, twenty-seven percent]
(7) Oral answer: the relationship between fraction and division.
Teacher's summary: We reviewed some knowledge about decimals and fractions. In order to facilitate comparison and calculation, fractions are often converted into decimals or decimals are divided into numbers. Let's learn this knowledge today. The interaction between fractions and decimals.
2. The method of learning the number of fractions.
Just now, we reviewed the meaning of decimals. Decimals represent tenths, hundredths and thousandths. So decimals can be written directly as denominators 10, 100, 1000, ...
(1) Give an example of 1: divide 0.9, 0.03, 1.2 1, 0.425 into components.
You can answer by name: say the meaning of each decimal first, and then turn it into a component number.
(2) induction.
A simple method to guide students to discover decimals through observation. Students can discuss it.
Decimal decimal, there are several decimal places, just write a few zeros after 1 as the denominator, and remove the decimal points of the original decimal places as the numerator; After the number of components, the number of quotation points can be reduced.
(3) feedback exercises.
Decimalize the following numbers. (After the class finishes writing, assign students to write on the slide)
0.7 6. 13 0.08 0.65 1.075
3. Learn how to convert fractions into decimals.
The teacher asked: Can these scores be directly converted into decimals according to the meaning of decimals? Ask the students to talk to each other and then answer by name.
The teacher asked: Can you convert these fractions into decimals according to the relationship between fractions and division? After the discussion, the students called the roll and answered:
(2) induction.
Guide the students to observe the characteristics of the denominator of these fractions and talk about how to turn them into decimals. Draw:
The denominator is fractional decimal 10, 100, 1000, ... You can directly remove the denominator. See how many zeros there are after the denominator of 1. Just count a few digits to the left from the last digit of the molecule and dot on the decimal point.
(3) feedback exercises.
Convert the following fractions into decimals. After the class finishes writing, ask the students to write it on the slide. )
[Revision: 0.1.73 2.09 0.601.14.7 5.83]
When revising, let the students talk about the method again and give guidance according to the students' questions.
Decimal number. Teachers guide students to observe the characteristics of denominator of these fractions. (The denominator is not 10, 100, 1000) Question: How did these fractions become decimals? Think about the relationship between fraction and division. After the students discuss, try to do it. Then call the roll.
When revising, let the students talk about the method, emphasizing that if you want to keep three decimal places, you should divide them to the fourth decimal place, and then keep the decimal place according to the rounding method, which is indicated by "√".
(5) induction.
Guide the students to observe the characteristics of the denominator of this group of fractions and talk about their decimal methods. After discussion, the conclusion is:
The denominator is not fractional decimal 10, 100, 1000, ..., so the numerator should be divided by the denominator; When it is not used up, you can keep a few decimal places according to the rounding method as needed.
(6) feedback exercises.
Convert the following fractions into decimals. (except endless, keep three decimal places. )
4. Consolidate the exercises.
(1) Guide students to read, question and solve doubts.
(2) Consolidate practice.
Number of decimal components below (1). The whole class has finished writing. )
0.5 0.8 1.07 0.85 7.25
(2) Line up each of the following decimals with its equivalent fraction.
When modifying, first talk about the method, which can be divided into decimals or fractions, and then compare them.
③ Extract the following scores.
[Revision: 0.5, 0.25, 0.75, 0.2, 0.4, 0.6, 0.8, 0. 125, 0.05, 0.04. ]
After the revision, the teacher explained that this is a commonly used "sub-small" data and should be kept in mind. Give time and let the students write it down.
5. Class summary.
Teachers and students * * * summarize the learning content of this lesson. Note that when emphasizing the reciprocity of fractions and decimals, the fourth decimal place should be removed from the inexhaustible ones, and three decimal places should be retained after rounding, which should be indicated by "≈". At the same time, it is pointed out that the integer part should not be lost when using fractions and decimals for reciprocal transformation.
The fourth teaching goal of fifth grade mathematics "the relationship between fractions and decimals"
1. Through teaching, students can understand and master the reciprocal method of fractions and decimals, and can skillfully and correctly reciprocal fractions and decimals.
2. Comprehensive use of the learned mathematical knowledge to cultivate students' ability to solve problems. 3. Cultivate students' awareness of applying mathematical knowledge to solve practical problems.
Important and difficult
Understand and master the reciprocal method of fractions and decimals.
training/teaching aid
Projection.
teaching process
(1) Newly awarded
For example, 2. Put the six numbers 0.7, 0.25,,, in descending order.
(l) Question: There are fractions and decimals in these six numbers. What should I do if I want to compare the sizes of these numbers?
Students may think of two ways: one is to convert fractions into decimals, and the other is to convert decimals into component numbers.
Question: Which method is simpler? Why? (Decimals are relatively simple) (2) Let students try decimals.
The teacher asked: The denominator is not fractions 10, 100, 1000…, how to convert it into decimals?
Students discuss and try to solve problems in groups, and then ask representatives to report and communicate.
There are two possible methods:
(1) Multiply the numerator and denominator by the same number at the same time, convert the fractions with the mother of 10, 100,1000 ... and rewrite them into decimals. = = =0.28
① Using the relationship between fraction and division, divide the numerator by the denominator to get decimals.
=7÷25=0.28
(1) Let students convert it into decimals.
Students try to solve it by themselves and see what goes wrong. (Denominator 45 cannot be converted into 10, 100, 1000 ... as denominators. When the numerator is divided by the denominator, there is infinite division. ) It is pointed out that when such a fraction is converted into decimal, the numerator can only be divided by the denominator. Under normal circumstances, if the numerator is divided by the denominator, a few decimals need to be reserved according to the method of "four hospitals and five people". This question needs two decimal places.
= 1 1÷45≈0.24
(4) Now, can you arrange these six numbers from small to large? Students do it independently.
(5) Summary: How many methods are there to convert fractions into decimals?
To guide students to summarize, the general method is: use numerator to present denominator (keep several decimal places as required when not exhausted). Special methods: ① When the denominator is 10, 100, 1000 ..., write it directly as a decimal. (2) When the denominator is the factor 10, 100, 1000 ..., the factorial mother is the fraction of 10, 1000 ....
(6) Complete the "doing" on page 98 of the textbook.
Let the students judge which fractions can be written as decimals first. What fractions can be divided into vowels?