The fifth grade mathematics unit 2 factor and multiple teaching plan (1)
Teaching objectives:
1, students master the method of finding the factor and multiple of a number;
2. Students can understand that the factor of a number is limited and the multiple is infinite;
3. Be able to skillfully find out the factors and multiples of a number;
4. Cultivate students' observation ability.
Teaching emphasis: master the method of finding the factor and multiple of a number.
Teaching difficulty: be able to skillfully find out the factors and multiples of a number.
Teaching process:
First, introduce new courses.
1. Show the theme map and ask the students to do a multiplication formula.
2. Teacher: See if you can read the following formula.
Xiu: Because of 2? 6= 12
So 2 is a factor of 12, and 6 is also a factor of 12;
12 is a multiple of 2 and 12 is also a multiple of 6.
3. Teacher: Can you talk about another formula in the same way?
(Name the students)
Teacher: Do you understand the relationship between factor and multiple?
Then can you find other factors of 12?
4. Can you write a formula to test your deskmate? Students write formulas.
Teacher: Who will work out a formula to test the class?
5. Teacher: Today we are going to learn factors and multiples. (Exhibition theme: factor multiple)
Pay attention to watch p 12 together.
Second, the new grant:
(a) looking for factors:
1, example 1: 18 What is the factor?
From the factor of 12, we can see that there is more than one factor of a number, so let's find the factor of 18 together.
Students try to finish: report
(The factors of 18 are: 1, 2, 3, 6, 9, 18).
Teacher: Tell me how you found it. (Student: Divide by division, 18? 1= 18, 18? 2=9, 18? 3=6, 18? 4=? ; Find one-to-one correspondence by multiplication, such as 1? 18= 18,2? 9= 18? )
Teacher: What is the minimum factor of 18? What's the biggest? When we write, we usually arrange it from small to large.
2. In this case, please look for the factor of 36 again.
The factors of Report No.36 are: 1, 2, 3, 4, 6, 9, 12, 18, 36.
Teacher: How did you find it?
Give examples of errors (1, 2, 3, 4, 6, 6, 9, 12, 18, 36).
Teacher: Is this ok? Why? No, because you only need to write one repetition factor, you don't need to write two sixes. )
Look carefully, what is the smallest and largest factor of 36?
It seems that the smallest factor of any number must be () and the largest must be ().
3. Which factor are you looking for? (18, 5, 42) Please choose one of them and write it in the exercise book, and then report it.
4, in fact, some factors of writing in addition to this writing, can also be expressed by set:
/kloc-factor of 0/8
Conclusion: We have found so many factors. How do you think to find them so as not to miss them easily?
Start with the smallest natural number 1, that is, start with the smallest factor and find all the way. In the process of searching, one by one, from small to uppercase.
(2) Find multiple:
1. We found the factor of 18 together. Can you find a multiple of 2?
Reports: 2,4,6,8, 10, 16,
Teacher: Why can't I find it?
How did you find these multiples? Student: Just multiply 2 by 1, 2, 3, 4,? )
So what is the minimum multiple of 2? Can you find the biggest one?
2. Ask the students to finish the questions 1 and 2: Find multiples of 3 and 5.
The multiples of Report 3 are: 3,6,9, 12.
Teacher: Is this ok? Why? How should I change it?
Rewritten as: multiples of 3 are: 3, 6, 9, 12,
How did you find it? (1, 2, 3 times 3 respectively)
The multiple of 5 is: 5, 10,15,20,
Teacher: To express the multiple of a number, in addition to this method of text narration, you can also use the set to express the first network of the new curriculum standard.
Multiples of 2, multiples of 3 and multiples of 5.
Teacher: We know that the number of factors of a number is limited, so what is the multiple of a number?
The number of multiples of a number is infinite, the minimum multiple is itself, and there is no maximum multiple.
Third, the class summary:
Let's recall, what did we focus on in this class? What did you get?
Fourth, work independently:
Complete Exercise 2, Question 1 ~ 4.
Teaching reflection:
Second lesson
Topic: Teaching design of the characteristics of multiples of 2 and 5.
Teaching objectives:
1, master the characteristics of multiples of 2 and 5.
2. Understand and master the concepts of odd and even numbers.
3. These characteristics can be used to judge.
4. Cultivate students' generalization ability.
Teaching emphases and difficulties:
1 is a characteristic of numbers that are multiples of 2 and 5.
2. The concepts of odd and even numbers.
Teaching tools: slides.
Teaching process:
First, review preparation
1, ask questions.
Name all the factors of 20.
② Name five multiples of 8.
What is the minimum factor of ③ 26? What is the maximum factor? What is the minimum multiple?
2. Fill in the number in the assembly circle as required.
Second, learn new lessons:
Characteristics of multiples of (1)2.
Teacher: (Exercise 2) What is the relationship between the number in the right set circle and the number in the left set circle?
Teacher: Please look at the numbers in the circle on the right. What are the characteristics of their single digits?
(The units are 0, 2, 4, 6, 8. )
Teacher: Please name several multiples of 2 to see if the operator meets this feature.
Students just give an example.
Teacher: Who can talk about the characteristics of numbers that are multiples of 2?
After the students answered, the teacher wrote on the blackboard: the number of units is 0, 2, 4, 6, 8, all multiples of 2.
2. Oral answer exercise: (Slide) Please fill in the following numbers in the circle as required (it is a multiple of 2, not a multiple of 2).
1,3,4, 1 1, 14,20,23,24,28,3 1,40 1,826,740, 1000,643 1。
After the students answered, the teacher introduced the definitions of odd and even numbers.
Written on the blackboard: written on the upper two assembly rings? Even number? ,? Odd numbers? .
Teacher: Should ellipsis be placed in the upper two assembly circles? Why?
After the students discussed, the teacher explained:
Among the finite numbers listed in this question, odd and even numbers are finite, but natural numbers are infinite, and so are odd and even numbers, so write ellipsis in the set circle.
Teacher: Have you ever met odd and even numbers in our daily life? What are they customarily called? (singular, even. )
3. Exercise: (Group the novels first, and then the whole class will answer them in unison. )
Name five multiples of 2. (Requirements: two digits. )
② Name three digits that are not multiples of 2.
③ Name even numbers within 15 ~ 35.
④ How many even numbers are there within 50? How many odd numbers are there?
(2) Characteristics of multiples of 5.
1, the teacher first draws two groups of circles on the blackboard, and then asks: Can you find out the characteristics of multiples of 5 like studying the characteristics of multiples of 2?
Fill in the numbers, observe and discuss. Choose a classmate to fill in the blanks on the blackboard when the teacher is on patrol.
Teacher: What are the characteristics of multiples of 5?
Teacher: Please give some examples of multi-digit verification.
Teacher: Tell me again what kind of number is a multiple of 5.
Blackboard: Numbers with units of 0 or 5 are multiples of 5.
2. Practice:
(1) In descending order, say a multiple of 5 within 50.
(2) (Slide) Which of the following numbers is a multiple of 5?
240,345,43 1,490,545,543,709,725,8 15,922,986,990。
(3) (Slide) Pick out the numbers that are both multiples of 2 and multiples of 5 from the following numbers. What are the characteristics of these figures?
12,25,40,80,275,320,694,720,886,3 100,3 125,3004。
After the students answered, the teacher wrote on the blackboard: the unit number is 0.
The teacher casually said a number, please immediately say whether this number is a multiple of 2 or 5, or both, and explain the basis for judgment.
Third, consolidate the feedback:
1. There are () multiples of 2 and () multiples of 5 among the natural numbers from 1 to 100.
2. Odd numbers less than 75 and greater than 50 are ().
3. The number in () is a multiple of 2 and 5 at the same time.
4. Use five numbers of 0, 7, 4, 5 and 9 to form a multiple of 2; A multiple of 5; Numbers that are both multiples of 2 and 5.
Class summary: What did you learn in this class? What did you get?
Teaching reflection:
The third category
Topic: Teaching design of multiple characteristics of 3.
Teaching objectives:
1, after looking for multiples of 3 in the natural number table within 100, I realized the characteristics of multiples of 3 on the basis of activities and tried to summarize the characteristics in my own language.
2. Feel the mystery of mathematics in the exploration activities; The value of experiential mathematics in the law of application.
Teaching emphasis and difficulty: it is the characteristic that a number is a multiple of 3.
Teaching process:
First, put forward the topic and look for the characteristics of 3.
Teacher: Students, we already know the characteristics of multiples of 2 and 5, so what are the characteristics of multiples of 3? Who can guess?
Health 1: Numbers with 3, 6 and 9 are multiples of 3.
Health 2: No, the numbers with 3, 6 and 9 are not multiples of 3. For example, l 3, l 6, 19 are not multiples of 3.
Health 3: In addition, numbers like 60, 12, 24, 27 and 18 are not 3, 6 and 9, but they are all multiples of 3.
Teacher: It seems that we can't determine whether it is a multiple of 3 just by observing the unit, so what are the characteristics of a multiple of 3? Today we are going to study together. (revealing the topic)
Teacher: Please find a multiple of 3 in the table below and mark it. (The teacher shows a digital table within 100, and the students have one. After the students' activities, the teacher organizes the students to communicate, and presents a form in which the students circle multiples of 3. ) (as shown below)
Second, independently explore and summarize the characteristics of 3:
Please find a multiple of 3 in the table below and mark it. (The teacher shows the table within 100, and the students use the table of p 18. After the students' activities, the teacher organizes the students to communicate, and presents a form in which the students circle multiples of 3. ) (as shown below)
Teacher: Please look at this table. What characteristics do you find in multiples of 3? Communicate your findings with your deskmate.
After the students communicate at the same table, organize the whole class to communicate.
Health 1: I found that only numbers within 10 are multiples of 3.
Health 2: I found that multiples of 3 appear every two numbers, regardless of horizontal or vertical.
Student 3: I've seen them all. The classmate's guess just now was wrong. A multiple of 3 may have ten numbers from 0 to 9.
Teacher: The number of digits is irregular, so is it regular?
Health: There are no rules. 1 ~ 9 These numbers have all appeared.
Teacher: Did the other students find anything else?
Health: I found that multiples of 3 are regularly arranged in a diagonal line.
Teacher: Your observation angle is different from that of other students, so are the numbers on each diagonal regular?
Health: From top to bottom, both serial numbers are ten digits increased by 1, while the single digits decreased by 1.
Teacher: What are the similarities between the number composed of ten digits plus 1 and single digits minus 1 and the original number?
Health: I found it? 3? The diagonal lines of the other two numbers 12 and 2 1 add up to three.
Teacher: This is an important discovery. What about the other diagonals?
Health 1: I found it? 6? The number on the diagonal, the sum of two numbers is equal to 6.
Health 2:? 9? The number on the diagonal, the sum of two numbers is equal to 9.
Health 3: I found several other columns, except that the sum of the numbers 30, 60 and 90 on the side is 3, 6 and 9, and the sum of other numbers is 12, 15, 18.
Teacher: Who can sum up the characteristics of multiples of 3 now?
Health: The sum of digits of a number is equal to 3, 6, 9, 12, 15, 18, etc. This number must be a multiple of 3.
Teacher: Actually, the numbers 3, 6, 9, 12, 15 and 18 are all multiples of 3, so how do you say this sentence?
Health: The sum of digits of a number is a multiple of 3, so this number must be a multiple of 3.
Teacher: Just now, we found the law from the numbers within 100, and obtained the characteristics of multiples of 3. If it is a number with more than three digits, are the characteristics of multiples of 3 the same? Please find a few more figures to verify.
Students write their own digital verification, then communicate in groups and come to the same conclusion.
The whole class read the conclusion in the book.
Third, consolidate the exercises:
Do it after p 19.
Fourth, the class summary:
What did you learn from this course?
Teaching reflection:
the fourth lesson
Topic: Teaching Design of Prime Numbers and Composite Numbers
Teaching objectives:
1. Understand the concepts of prime number and composite number, judge whether a number is prime number or composite number, and classify natural numbers according to the number of divisors. 2. Cultivate students' ability of independent exploration, independent thinking and cooperative communication.
3. Cultivate students' spirit of daring to explore scientific mysteries and fully display the charm of mathematics itself.
Teaching focus:
1, understand and master the concepts of prime numbers and composite numbers.
2. Learn to judge whether a number is prime or composite.
Teaching difficulties:
Distinguish between odd numbers, prime numbers, even numbers and composite numbers.
Teaching process:
First of all, explore and find, summarize the concept:
1, Teacher: (Show three identical small squares) The side length of each square is 1. How many different rectangles can you spell by using these three squares to make a rectangle?
Students think independently, and then the whole class communicates.
2. Teacher: How many different rectangles can these four small squares spell?
Students think independently, raise their hands and answer after imagination.
3. Teacher: Students, think again. If there are 12 such small squares, how many different rectangles can you spell?
Teacher: I think many students already know it without drawing. (Name it)
4. Teacher: Students, if there are more squares given, what do you think will happen to the number of different rectangles spelled out?
The students almost said with one voice: the more the better.
Teacher: Are you sure? Guide the students to discuss. )
5. Teacher: Students, sometimes a small square can only spell a rectangle, and sometimes it can spell multiple rectangles. Do you think you can only spell one when the number of small squares is what? When can you spell more than one rectangle? And give an example.
Let the students discuss in groups first, and then communicate with the whole class. The teacher writes on the blackboard according to the students' answers.
Teacher: Students, like the numbers above (3, 13, 7, 5, 1 1), we call them prime numbers in mathematics, and the numbers below (4, 6, 8, 9, 10,/kloc).
After students think independently, communicate in groups, and then communicate with the whole class.
Guide students to summarize the concepts of prime numbers and composite numbers, and write them on the blackboard with students' answers: (omitted)
6. Let the students illustrate which numbers are prime numbers and which numbers are composite numbers, and give the reasons.
7. Teacher: What do you think? 1? What is the number?
Let the students think independently and then discuss.
Second, hands-on operation, quality table.
1, the teacher shows: 73. Ask the students to think about whether it is a prime number.
Teacher: It is not easy to know what 73 is at once. It would be convenient if there is a quality table to check. (The students all say? Is it? . )
Teacher: Where did this watch come from?
(The teacher shows the number table within 100) This number is 1 to 100, not a prime number table. Can you find out the prime numbers within 100 and make a prime number table? Who wants to talk about their ideas? Let the students fully express their ideas. )
2. Let students make high-quality forms by hand.
3. Collective communication.
Third, practice to consolidate:
Complete Exercise 4, Questions 1 and 2.
Four. Topic overview:
The fifth grade mathematics unit 2 factor and multiple teaching plan (2)
I. Teaching content
1. Factor and multiple.
Characteristics of multiples of 2.2, 5 and 3.
3. Prime numbers and composite numbers.
Second, the teaching objectives
1. Make students master the concepts of factor, multiple, prime number and composite number, and know the connections and differences between related concepts.
2. Make students master the characteristics of multiples of 2, 5 and 3 through independent exploration.
3. Gradually cultivate students' mathematical abstract ability.
Third, the arrangement characteristics
1. Simplify concepts and reduce students' memory burden.
(1) no longer appears? Can be divided? The concepts of concept, factor and multiple come directly from the multiplication formula.
(2) There is no formal teaching? Decomposition factor? , only as an introduction to reading materials.
(3) Common factor, greatest common factor, common multiple and least common multiple are all moved to? What is the meaning and nature of fractions? As a knowledge base of reduction and generalization, unit highlights its application.
2. Pay attention to the abstraction of mathematics.
Number theory knowledge itself is abstract. Students should also pay attention to cultivating abstract thinking in senior three.
Fourth, specific arrangements.
(1) factor and multiple
1. The concepts of factor and multiple.
use