Teaching content:
1. Multiplication of fractions
2. Fractional mixed operation
3. Solve problems with scores
Teaching material analysis: This unit is based on integer multiplication, the meaning and nature of fractions, and it is also an important basis for learning fractional division and percentage. Like the calculation teaching of integers and decimals, the calculation of fractional multiplication also implements the concept of "let students experience and understand mathematics in real situations" put forward by the standard, leads to calculation problems through practical problems, and arranges certain contents to solve practical problems in practice, so as to enrich the practice form, strengthen the connection between calculation and practical application, and cultivate students' awareness and ability of applying mathematics. According to the idea of compiling this textbook, this unit will arrange and solve some special quantitative relations separately.
Three-dimensional target:
Knowledge and skills: enable students to understand the meaning of multiplying fractions by integers and master the calculation method of multiplying fractions by integers. Enable students to apply the calculation rules of fractional multiplication by integer and make calculations skillfully. Through observation and comparison, cultivate students' abstract generalization ability. Know the meaning of fractional multiplication by integer and learn the calculation method of fractional multiplication by integer.
Process and method: Experience the meaning of fractional multiplication by integer and the formation process of calculation rules, and experience the mathematical ideas and methods of induction and generalization. In the process of calculating fractional multiplication with integers, we can perceive the calculation method.
Emotion, attitude and values: by guiding students to explore the internal relationship between knowledge, stimulate students' interest in learning, feel the charm of mathematical knowledge and understand the beauty of mathematics.
Teaching methods and learning methods: Through demonstration, let students have a preliminary understanding of arithmetic.
Instruct students to summarize the calculation method of multiplying scores by integers through experience.
Teaching emphasis and difficulty: let students understand the meaning of multiplying fractions by integers. Master the calculation method of fractional multiplication by integer;
Guide students to summarize the calculation method of fractional multiplication by integer.
Teaching hours: 10 class hours
Lesson 65438
Total semester 1 class hour.
Teaching topic score multiplied by integer
The teaching time of active and reserve teachers is 2065438+2004.
Date 20 15
teach
study
eye
Standard knowledge
and
On the basis of students' existing fractional addition and basic meaning, combined with life examples, through the study of fractional addition formula, students can understand the meaning of fractional multiplication by integer, master the calculation method of fractional multiplication by integer, and skillfully use the calculation rules of fractional multiplication by integer to calculate.
process
and
Methods Through observation and comparison, students are guided to sum up the calculation law of fractional multiplication by integer through experience, and their abstract generalization ability is cultivated.
mood
attitude
valence
Values guide students to explore the internal relationship of knowledge and stimulate students' interest in learning. Through demonstration, students can have a preliminary understanding of arithmetic, and feel the charm and beauty of mathematical knowledge in this process.
The focus of teaching is to let students understand the meaning of fractional multiplication by integer and master the calculation method of fractional multiplication by integer.
Teaching difficulties guide students to summarize the calculation rules of fractional multiplication by integer.
Intuitive demonstration of teaching methods and learning methods
Teaching preparation and means courseware
The process of teaching and learning, preparing lessons for the second time
Teaching content:
Page 2, for example 1 and "Do it", practice 1 1-3.
Teaching process:
Pave the way for pregnancy
1. Show the review questions. (slide)
What does (1) mean by integer multiplication?
(2) List and tell the meanings of multiplicand and multiplier in the formula.
What is five 12? How much is nine 1 1? How much is eight sixes?
(3) Calculation:
When calculating, ask the students: What are the characteristics of this problem? What is the molecule in calculation? Let the students see that all three addends are the same. When calculating, the result of three consecutive additions is the numerator, and the denominator remains unchanged.
2. Lead the topic.
Is there a simple algorithm for fractional addition? Today we are going to learn fractional multiplication. (Title on the blackboard: Fractions multiplied by integers)
(2) Explore new knowledge.
1. The meaning of multiplying teaching scores by integers.
Give an example of 1 and read the questions by name.
(1) Analysis and demonstration:
Teacher: Everyone has a piece of cake. Is it enough for everyone? (Not enough) Then show three pie charts like a textbook. Q: How many pieces did one person eat and how many pieces did three people eat? Let the students see from the picture that three people ate three pieces. Ask the students to use what they have learned before to answer how many pieces did three people eat? The teacher drew braces under the three sectors and marked them? When reviewing, the teacher wrote:++= (Block) on the blackboard. (The teacher put together three double-layer fan-shaped pictures to make a picture of a cake.)
(2) observation and guidance:
What are the characteristics of the three addends in this question? Let the students see that the scores of the three addends are the same. The teacher asked: How to find the sum of three identical scores is easier? Guide students to enumerate multiplication formulas. Teacher writes on the blackboard: Then inspire the students to say that they want the sum of three additions.
(3) Compare the similarities and differences between sum 12×5:
Tip: Compare the meanings and characteristics of the two formulas. Let the students discuss.
Through discussion, students can draw the following conclusions:
Similarity: These two expressions have the same meaning.
Difference: Fraction multiplied by integer, 12×5 is integer multiplied by integer.
(4) Summary:
The teacher made it clear that these two expressions have the same meaning. Who can sum up the meaning of these two expressions in one sentence? Guide the students to say that they all mean finding the sum of several identical addends. )
2. The calculation rules of multiplying teaching achievement by integer.
(1) deduction algorithm:
Multiply the meaning of an integer by a fraction.
Q: What does this mean? Guide the students to say that they want the sum of three. Blackboard:++ Students do the math, and the teacher writes on the blackboard. Tip: How to write a simple method of adding three twos in a molecule? Write on the blackboard after the students answer: (block) The teacher explains that the addition formula in the middle of the calculation process is to explain the calculation, and it is omitted during the calculation. (adding dotted lines while talking)
(2) Guiding observation: What is the relationship between the numerator, denominator and two numbers in the formula? (discuss with each other)
Observation result: The numerator part of 2×3 is the numerator 2 multiplied by the integer 3 in the formula, and the denominator has not changed.
(3) Summary:
Please summarize the calculation method according to the observation results. (discuss with each other)
Report results: (Let more students report) Let students draw a conclusion: the product of numerator 2 and integer 3 of a fraction is a numerator, and the denominator remains unchanged.
According to the calculation process, it is clearly pointed out that the numerator and denominator can be divided first and then multiplied. The approximate number after reduction should be aligned with the original number up and down. Then let the students calculate according to the simple method.
Through cooperative learning, students are inspired to learn, summarize and induce, and their language expression ability and logical thinking ability are cultivated.
3. Feedback exercise:
(1) Title 1 on page 2 of the textbook.
When correcting mistakes, let the students say what the multiplicand and multiplier in multiplication mean.
(1) The second question of "doing" on page 2 of the textbook.
Teacher's tip: When multiplying, if the numerator and denominator are divisible, divide the points first.
(1) Exercise 1No. 1, 2, 3 on page 6 of the textbook.
Students complete independently and communicate collectively. Let the students talk about their ideas.
(3) class summary.
What did we learn in this class? Guide the students to review and summarize.
Homework design exercise 1, questions 2 and 3.
Fractional multiplication of blackboard writing design
second kind
Total class hours of the second class this semester
The Teaching Theme of Fractional Multiplication (2)
The teaching time of active and reserve teachers is 2065438+2004.
Date 20 15
teach
study
eye
Standard knowledge
and
Skills combined with specific situations to understand the meaning of multiplying a number by a score is "what is the score of a number".
process
and
Methods By organizing students to carry out mathematical activities such as transfer, analogy, induction and communication, students' ability of analogy and induction is cultivated.
mood
attitude
valence
Through a wide example of the application of multiple fractions, values educate students' learning objectives and stimulate their learning motivation and interest.
The focus of teaching is to understand the meaning of multiplying a number by a fraction and master the calculation method of multiplying a number by a fraction.
Deduce and summarize the laws in teaching difficulties.
Intuitive demonstration of teaching methods and learning methods
Teaching preparation refers to wall charts, slides or multimedia courseware made according to examples.
The process of teaching and learning, preparing lessons for the second time
Teaching content:
Page 3 of the textbook and related teaching contents "
Teaching process:
First, check the import.
1, calculate the following questions and tell the calculation method.
×4 ×4 × 14×
2. Introduction: In this lesson, we will continue to learn the problem of fractional multiplication. (blackboard writing topic)
Second, explore new knowledge.
(A) the meaning of a number multiplied by a fraction
1. Projection demonstration example 2.
(1) Question1:How many liters are there in 3 barrels of water?
List the formulas by name: 12×3.
Question: What do you think?
Inspire the students to draw a conclusion: "How many liters are there in three barrels of water?" Is to find three 12L, that is, what is three times of 12L. (2) Question 2: How many liters of bottled water?
List the formulas by name: 12×.
Q: According to what?
Inspire students to think: a barrel is half a barrel. How many liters is it? That is, what is half of 12L, that is, what is 12L.
(3) Question 3: How many liters of bottled water?
List the formulas by name: 12×.
Question: What do you think?
Inspire students to think: How much is the bucket? Is to find the number 12L.
2. Combined with the above questions, do you know what the expressions "12×" and "12×" mean respectively?
What is 12× 12L? What is 12L?
3. Summary: The meaning of multiplying a number by a fraction.
Multiplying a number by a fraction means finding a fraction of this number.
4. Complete the "Do" on page 3 of the textbook.
Introduction: This question asks how many kilograms you have eaten, that is, how many kilograms you have eaten in 3 kilograms.
(two) the calculation method of the score multiplied by the score.
Projection display example 3.
Uncle Li's family has a hectare of land. Potato planting area accounts for, and corn planting area accounts for.
1. Question 1: How many hectares is the potato planting area?
(1) Question: What is the potato planting area? What is it? How to go public?
(In fact, how many hectares is it? The list is: ×. )
(2) Explore the calculation method of ××.
Ask the students to take out a square piece of paper ready to represent one hectare, and draw it first to represent one hectare.
(2) Draw hectares.
The tour guide understands: How many hectares do you want? That is, divide the hectare into five points on average, and take 1 of them.
③ Observation and communication.
Look at the rectangular paper in your hand and think about it. How many hectares are there? what do you think?
Let the students communicate in groups first, and then organize the whole class to communicate.
Through communication, we can get how many hectares are needed, that is, divide the hectares into 5 points on average, and take 1 of them. That is to say, divide 1 hectare into (2×5) portions, and take 1 portion, that is, × 1= =.
Blackboard writing: × = = (hectare)
2. Question 2: How many hectares of corn is planted?
(1) Students independently list formulas: ×
(2) Question: What is "×"? Can you show it in color?
⑶ Students begin to operate and exchange calculation methods and ideas.
As before, this paper is divided into (2×5) pieces equally, except that you can get × = (hectare) by taking 3 pieces.
3. The calculation method of the score multiplied by the score.
Discuss in groups first, and then report and communicate.
Calculation rules: fractional multiplication, molecular multiplication and product multiplication, integer multiplication and denominator multiplication. (blackboard writing)
Third, consolidate practice.
1. "Doing" on page 4 of the textbook 1.
This question is an exercise about the meaning of multiplying a number by a fraction.
When organizing exercises, students can read and understand independently, and fill in the textbook first. Then report by name, and let the students say what they think.
2. "Do" question 2 on page 5 of the textbook.
This is an exercise of looking at pictures and calculating. Through practice, cultivate students' observation ability and deepen their understanding of the method of multiplying fractions by fractions.
When organizing exercises, students can fill in the picture first, and then let them talk about the thinking process.
3. The third question of "doing" on page 5 of the textbook.
This problem is to use the knowledge of fractional multiplication to solve practical problems, which can deepen the understanding of the meaning of a number multiplied by a fraction and consolidate the calculation method of integer multiplied by a fraction.
4. "Exercise 1" questions 4 and 5 on page 6 of the textbook.
First, students calculate independently and let them speak their minds.
Fourth, the whole class summarizes.
Questions 3 and 4 in exercise 2 of homework design.
Fractional multiplication of blackboard writing design
12×3
Think: find three 12L, that is, find.
What is the triple of 12L? (1) How many hectares of potatoes are planted?
12×× = (hectare)
Think about it: find half of 12L, that is, how many hectares of corn are planted?
What is 12L? × = = = (hectare)
12 times the fraction, using the product of molecular multiplication as the molecule,
Think: What is 12L? Use the product of denominator multiplication as the denominator.
Reflection on one's own experience