Knowledge and skills, processes and methods;
1. Understanding the meaning of factors and multiples from business activities can determine whether a number is a factor or multiple of another number.
Emotional attitudes and values:
2. Cultivate students' abstract generalization ability, and penetrate the view that things are interrelated and interdependent.
3. Cultivate students' consciousness of cooperation, inquiry and love of mathematics learning.
Teaching emphases and difficulties:
1, the meaning of factor and multiple and their interdependence.
2. The method of finding the factor or multiple of a number.
Teaching preparation: courseware
Teaching process:
Process 1: Introducing new courses
Process 2: Understanding multiples and factors
Process 3: Explore the method of finding the factor of a number.
Process 4: Complete? Try it? Summarize the characteristics of a numerical factor.
Process 5: Explore the method of finding the multiple of a number.
Process 6: Complete? Try it? Summarize the characteristics of multiples of a number
Process 7: Complete Smart Paradise
Process 8: Complete the Question Paradise
Process 9: Math Games
Process 1 1: course summary
Process 10: Organize students to leave.
The first paragraph: introduce new lessons.
Process 1: Introducing new courses
Teacher: Make a brain teaser before class to see who is the cleverest.
On Sunday morning, there are many people boating in the park. There are two fathers and two sons on one of the ships, but there are only three people on board. Do you know what happened?
(Students express their opinions)
Today, shall we invite these three people to my classroom? Can you introduce Xiao Lao and Lao Li around Da Li? (Students say)
Teacher: Can we separate that Da Li is the father? (Can't) Why?
Lead to interdependence (blackboard writing)
There is a father-son relationship in life, and so does our mathematics. Today, we will learn factors and multiples together.
The second paragraph: Understanding multiples and factors
Process 2: Understanding multiples and factors
(A) the concept of learning factors and multiples
1. Make a rectangle with 12 pieces of square paper of the same size prepared before class. Before and after in groups of four.
Requirements:
(1), you can pose several completely different rectangles when you see a * * *.
(2) Think about how to use multiplication formula to represent your swing.
Please put it at the back of your textbook for the convenience of demonstration.
(Student hands-on operation and report)
Teacher: Would you please use the multiplication formula to express your swing?
Health: 1? 12= 12 2? 6= 12 3? 4= 12
Teacher: In order to avoid repetition, we can only choose one of the formulas. We have learned before, what are the numbers before and after multiplication? What is the number after the equal sign? (Product) The factor and product here are the names of the parts of the multiplication formula. In fact, there is interdependence between the elements and products mentioned in our class. Use 3? 4= 12 For example, mathematically, 12 is a multiple of 4, 12 is also a multiple of 3, and both 4 and 3 are factors of 12. Here, factors and multiples are interdependent. It cannot be said in isolation that 3 is a factor or a multiple of 12. This is what we are going to study today: multiples and factors.
Teacher: According to the other two multiplication formulas, will students say which number is a multiple of which number and which number is a factor of which number? Please communicate with each other at the same table (student activities).
Teacher: 12? 1= 12, 12 is a multiple of 1, 12 is also a multiple of 12, 12 and 1 are both/kloc-0. 6? 2= 12, 12 is a multiple of 6, 12 is also a multiple of 2, and both 6 and 2 are factors of 12. Are you right?
Teacher, there are two formulas in this book. Can you name them?
8? 9=72 18? 3=6
(Ask the students to talk about it)
Teacher: Students, multiples and factors refer to a relationship between two natural numbers, so we must find out who is whose multiples and who is whose factors. The teacher would like to add a point. For convenience, when we study, the numbers mentioned generally refer to natural numbers that are not zero.
The third paragraph: explore the method of finding multiples and factors.
Process 3: Explore the method of finding the factor of a number.
Teacher: How do students find the factor of a number? Are students willing to think independently and try to solve them? Face new problems and see who can challenge success.
Teacher: Can you find all the factors of 36? Please try to write it in your exercise book.
Student report (student activities)
Teacher: Starting from 1, we have to multiply two numbers by 36, so we can write the factor of 36 as a group of two until we find the closest multiplier. To solve this problem, we must first consider what the factor of 36 is. If the product of two numbers is 36, then both numbers are factors of 36. For example 1? 36=36, then 1 and 36 are all factors of 36.
Teacher: See if the teacher's filling method is the same as yours.
Teacher: To find the factor of a number, you can think of multiplication formula or division formula, but you should think methodically to avoid repetition or omission.
Process 4: Complete? Try it? Summarize the characteristics of the factors of a number
Teacher: Let the students write down the factors of your favorite numbers in a way you like or are familiar with. (Student activity) The camera looks for the students' blackboard writing.
Teacher: What do you find by observing the factors of the numbers written by the students above? Students say (complete the form)
Teacher's summary: the smallest factor is 1, and the biggest factor is oneself; The number of factors of a number is limited.
Write down all the factors of your student number.
Process 5: Explore the method of finding the multiple of a number.
Teacher: The students already know what multiples are, what multiples of that number are, and how many are there? This is what we will study next. How many multiples of 3 can you find?
Teacher: Students, think about it first. What number is a multiple of 3? How can I accurately write a multiple of 3? Share your thoughts with the students in the group. (Student activities)
Teacher: Students will definitely think that the multiple of 3 is the product of 3 times a natural number other than 0. Like 3? 1=(3),3? 2=(6),3? 3=(9), and the numbers in brackets are all multiples of 3. In this way, according to the order from small to large, we can systematically tell the multiples of 3 by multiplication, namely: 3, 6, 9, 12, 15, 18. Can you complete all multiples of 3? If you can't finish talking, how should you express the answer to the question? Because the number of multiples of 3 is infinite, you should use ellipsis to express the result completely when writing.
Process 6: Complete? Try it? Summarize the characteristics of multiples of a number.
Teacher: Let the students write multiples of 2 and multiples of 5 in this way. Pay attention to think in sequence and express the results in a standardized way. (Student activities)
Teacher: Check the answers with your classmates. If you make mistakes, you must analyze the reasons and correct them. (Check the answer)
Teacher: Now we have found a method to find the multiple of a number. We can find the multiple of 3, 2 and 5 by this method. Please observe the example above. Can you find the characteristics of a multiple of a number? Speak your mind boldly. (Student activities)
Teacher's summary: after careful observation, students will find that the minimum multiple of a number is itself, and there is no maximum multiple; The multiple of a number is infinite.
The fourth paragraph: deepen understanding and consolidate methods.
Process 7: Complete Smart Paradise
Teacher: Let's use the knowledge of multiples and factors to complete the paradise of wisdom. For each column in the table? Just pay RMB? How are they calculated? What do they have in common? How many multiples can you name? Can you complete a multiple of 4?
Teacher: Please consider doing the third question. First fill in the form, then discuss and answer the following questions: What is each column in the form? How many people are there in each row? How do you count the number of rows? And then what? How many people are there in each row? What numbers are 24? What inspiration did you get in the process of filling out the form? (Student activities)
Teacher: 24? 3=8,? 4=6,? 6=4,? 8=3,? 12=2,? 24= 1, in the table? Line number? And then what? How many people are there in each row? Are all factors of 24. In the process of filling in the form, we will find it more convenient to find out the factors of a number one by one.
Process 8: Complete the Question Paradise
Judge right and wrong first, and then talk about the reasons for your own judgment.
Paragraph 5: Math Games
Process 9: Math Games
Teacher: Please take out the card with the student number on it. Let's play a game together. Take a look and think about whether the number on your card meets the following conditions. If so, please hold up the card and wave it. (Courseware shows) I'm 5, I'm looking for my multiple; (Student activities) I am 24, and I am looking for my factors; (Student activity) I am 1, and I am looking for my multiple; I'm 30 years old and I'm looking for my factors. (Student activities)
The sixth paragraph: class summary
Process 10: course summary
Teacher: Students, in this lesson, we learned multiples and factors, and explored the method of finding multiples and factors of a number. According to the multiplication formula, we can multiply this number by 1, 2, 3 respectively to find its multiple. The number of multiples of a number is infinite, the minimum multiple is itself, and there is no maximum multiple. To find the factor of a number, you can think of a multiplication formula, and write a number as the product of the multiplication of two numbers, and the multiplier is the factor of this number; You can also think of a division formula. Divide 1, 2 and 3 by a number in turn, and you can get the integer quotient. Divider and quotient are its factors. When writing factors, it is more convenient to write them in one-to-one correspondence order according to formulas, and it is not easy to miss or repeat them. The number of factors of a number is limited, the smallest factor is 1, and the largest factor is itself.
Process 1 1: organize classes.
Organize students to leave in batches.
(1) Students with student numbers not less than three factors should leave first; (2) Please ask students with only two factors to leave; (3) Please come with me if the student number is only a factor.