Teaching Design of Simple Calculation of Fractional Multiplication (1)
Topic: simple calculation practice class
Teaching content: 15 pages? /kloc-exercise 3 on page 0/6.
Teaching objective: 1. Further understanding of the operation law of integer multiplication is not only applicable to decimal and integer multiplication, but also to decimal multiplication, which makes the calculation simple.
2. Master the rules of multiplication and perform simple decimal multiplication.
3. Cultivate students' thinking flexibility and knowledge transfer ability.
4. Feel the rigor and simplicity of mathematical knowledge and enjoy the profundity and endless fun of mathematical knowledge.
Teaching process:
First, review the learned multiplication formula and illustrate it with examples (give an example of integer, decimal and fraction, and tell the main calculation process)
1, multiplicative commutative law: a? b=b？ a
2, the law of multiplicative association: (a? b)？ c=a？ (b？ c)
3. Multiplicative distribution law: (a+b)? c=ac+bc
2. summary.
The arithmetic of integer multiplication is also applicable to fractional multiplication.
Teacher: By applying these multiplication laws, some calculations can be simplified.
Second, basic exercises (the teacher chooses a few questions from them, so that students can express their ideas? )
1, oral calculation:
24? + ? 57 + ? 2 - 1
+ - 1- - + - + ? 9 +
2. What have we learned? What do you know through study?
3, blackboard writing topic (simple operation exercise of fractional multiplication)
4. Division exercise: (After the exercise, talk about the purpose of division) (round up the whole number to make the calculation easier and faster)
9 3
5. Fill in the appropriate numbers or symbols in □ or □, and explain what algorithm is used?
( 1) 25=□? (□? □)
(2) =(□? □)? □
(3) ? ( 15? )=□? (□? □)
(4) 25? 4=□? □+□? □
(5) 7? =□? □〇□? □
(6) 1? 25=□? □〇□? □
(7) 54? (- )=□? □〇□? □
6. Teacher's summary: This exercise makes us touch the law of multiplication again at zero distance, which makes us feel that the law of multiplication is not only applicable to integers and decimals, but also to fractional multiplication, but when using it, it is the most important thing to use it correctly.
Third, deepen the practice:
1、? I can do it. , with a simple method to calculate:
(- )? 60 ? +? 25? 8 ? ( 15? )?
Requirements: Practice with the board. Post-evaluation and proofreading: tell me what you think.
Summary: If you want to do the calculation quickly and correctly, you must first have good calculation habits and answer according to the steps of finding, finding, calculating and checking. Whether the calculation can be simplified depends on the examination questions. In the calculation, we should look forward and look back, choose the method flexibly according to the specific situation and answer correctly, so as to complete the calculation quickly and correctly.
2、? I'm Bao Gong? ：
(1) is 27? The correct and reasonable method is ()
A, according to the law of integer multiplication. b、27？ =(28- 1)? =28? -
c、27？ =27-27? D, unable to determine
(2) +? +? +? +? +? +?
=+ + = + ? ( + ) = ? ( 1 + + )
=+ + = + = ? 2
= ( A ) = ( B ) = ( c)
Requirements: Are all three methods correct? Do you think () algorithm is more reasonable and simpler?
Conclusion: Through this exercise, we can see the diversity of algorithms, but among many algorithms, we should choose the best algorithm to achieve the purpose of simplification. This is what we need.
3、? Test you? How to calculate the following questions as simply as possible?
? 10 1- 99 + ( + )?
? + ? - 3? 25 36? ( - )?
Requirements: (1) Students study in cooperative groups.
(2) Students report and exchange ideas and learning achievements.
Fourth, expand the exercise:
? Challenge yourself! ? Let's have a look. Whose method is the most ingenious?
87 ? 3/86 26? 32?
Five, the class summary:
What did you learn from this lesson? Or have any new gains and ideas to talk about.
Assignment of intransitive verbs: ellipsis
(1) Observe the formula and tell me what its characteristics are.
(2) What do you think should be simpler?
Students think independently first and then communicate in groups.
Teaching Design of Simple Calculation of Fractional Multiplication (Ⅱ)
course content
The teaching content of this unit includes three parts: the calculation method of fractional multiplication, the solution of fractional multiplication and the understanding of reciprocal.
1. The calculation of fractional multiplication includes fractional multiplication of integers, fractional multiplication of fractions, simple operation of fractional multiplication, and mixed operation of fractional multiplication and addition and subtraction.
2. Solving problems includes finding a number score, one-step and two-step application problems.
3. The understanding of reciprocal includes the meaning of reciprocal and the method of finding the reciprocal of a number.
The teaching content of this unit is that students have mastered the meaning of integer multiplication and fraction. Calculation of properties and fractions addition and subtraction. Learning this unit well can not only solve related practical problems, but also be an important basis for learning fractional division and fractional mixed operation in the future.
Teaching objectives
1. Knowledge and skills
(1) enables students to understand and master the calculation method of fractional multiplication, and to calculate correctly and skillfully.
⑵ Make students master the mixed operations of fractional multiplication and addition, multiplication and subtraction, understand that the laws of integer multiplication are also applicable to fractional multiplication, and can apply these laws to simple operations.
(3) Let students learn how to solve the problem of finding the score of a number.
(4) Make students understand the meaning of reciprocal and master the method of finding reciprocal.
2. Process and method
⑴ After exploring the calculation method of fractional multiplication, we found and summarized the calculation method of fractional multiplication.
(2) exploration? What is the score of a number? Problems are organically combined with solving practical problems.
⑶ Let students experience independent thinking, cooperative communication, questioning and feedback to understand and master what they have learned.
3. Emotional attitudes and values
(1) Through learning activities, students can feel the scientific and rigorous conclusion of mathematics, be curious about mathematics and improve their interest in learning.
⑵ Let students further understand the close relationship between mathematics and real life when solving related problems.
Important and difficult
1. Focus
Calculation method of (1) fractional multiplication.
(2) Find out what the score of a number is.
2. Difficulties: the calculation method of fractional multiplication.
3. Do you understand? Multiplying a number by a fraction means finding the fraction of a number. The truth.
Reflections on the teaching of simple calculation of fractional multiplication
The simple calculation of fractional multiplication is based on students' learning how to use the multiplication law to make integer and decimal multiplication simple and how to add, subtract, multiply and divide fractions. Through teaching, students can further understand the operation law of integer multiplication, which is not only applicable to decimal and integer multiplication, but also applicable to decimal multiplication, making the calculation simple and convenient. It is helpful to improve the calculation efficiency and practical application.
This lesson is just a lesson about calculation. My design is based on students' self-study, supplemented by group discussion, based on bold speculation, verified by examples and summarized collectively. In this process, students are completely masters of learning, and I am only an auxiliary guide, including the design of exercises, which fully embodies this concept.
I thought that my classmates had studied the simple operations of integers and decimals, and the simple operations of fractional multiplication only applied the laws of multiplication and exchange, association and distribution, so they must have mastered it very well. It turns out that the effect of class is not bad, but the error rate in homework is extremely high. What's the problem? I reviewed this class and found that my teaching was trying to embody the spirit of curriculum reform. The whole class adopts the methods of letting students preview feedback, giving examples independently, trying to solve problems, exchanging discussions and summarizing independently. Teachers who strive to make students finish the class will never replace them, and cultivate students' ability of independent learning and problem solving. However, it ignores the most fundamental teaching goal of making students understand knowledge. Because there are no examples in the textbook and the exercises are too simple, students often don't need to think too much, so the Protestant problem is solved, which greatly reduces the space for students to think. How to play the role of teaching? How to cultivate students' flexible and simple computing ability? After thinking, I think we should start with the following points in the teaching of simple calculation:
We can't rely solely on imitation and memory.
It is an important way for students to practice, explore independently, cooperate and communicate, and strengthen the connection between mathematics and the real world. In teaching, I asked some students to describe the law of addition in words. As a result, none of them described it clearly. Instead, they are familiar with the operation rules expressed in letters and ask them why they do so. Answer in writing. I think that if students can give examples with practice, and pay attention to analyzing formulas through actual situations, they can help students intuitively understand the operation rules. The effect will not only deepen the understanding of the law, but also feel the close connection between mathematical calculation and life, and improve the ability to solve problems. Using two methods to solve problems reflects the diversity of students' thinking modes and thinks and solves problems from different angles. After the diversification of the algorithm, we should take this opportunity to establish a simple operation model: to lay a solid foundation for the flexible and reasonable simple operation of the later variants. With the help of the realistic prototype of mathematical knowledge, we can mobilize students' life experience, help students understand the operation rules they have learned, and construct personalized knowledge meaning. Secondly, mixed operation and simple operation are confused, and simple operation is misused. In addition, the distribution law is the most wrong one.
In the future teaching, I want students to observe more and draw more operation sequences, which greatly reduces mistakes.
Guess you like:
1. Mathematical Fraction Multiplication Manuscript
2. The teaching design of multiplication and distribution law.
3. Teaching design of table multiplication in the second grade of mathematics.
4. Mathematical Fractional Multiplication Teaching Reflection Mode
5. Teaching design of multiplication algorithm and simple operation in grade four.
6. Write newspaper pictures by fractional multiplication and division.