Design of primary school mathematics teaching plan ⅰ. Mathematics teaching plan of multiplication and operation law
course content
Page 17 ~ 18 Grade 4, for example 1 ~ 2, Exercise 4, Question 1
Teaching objectives
1. Experience the process of exploring and discovering multiplicative commutative laws and associative laws in specific situations of calculation and problem solving.
2. Understand and master the multiplicative commutative law and associative law, and preliminarily use these two algorithms to explain the reasons for calculation.
3. Experiencing mathematics is closely related to daily life, thus cultivating students' ability to independently explore and apply mathematical knowledge to solve simple practical problems.
Teaching focus
Explore and discover multiplicative commutative laws and multiplicative associative laws in specific situations.
teaching process
First, create scenarios and explore new knowledge.
1. Teaching examples 1
Draw an example of 1 Students can solve problems independently and then communicate with each other in groups.
Blackboard: 9×4=36, 4×9=36.
Students observe the blackboard and think: What are the characteristics of these two formulas?
Blackboard: 9×4=4×9.
Teacher: Can you still write such regular formulas?
The formula given by the students on the blackboard.
Such as: 15×2=2× 15.
8×5=5×8 ……
Teacher: Look at these formulas. What did you find?
Student 1: Two factors exchange positions, and the product remains unchanged.
Student 2: This is called multiplicative commutative law.
Teacher: Can you express the multiplication and commutation law in your favorite way? Students communicate after thinking independently.
Teacher: If two numbers are represented by A and B, how can this rule be expressed? a×b=b×a
2. Teaching Example 2
Example 2: Scenarios, oral mathematical information, problems solved.
Students think independently and answer in columns.
Then communicate ideas and methods to solve problems in groups.
The class report is written on the blackboard by the teacher.
8× 24× 68× 24× 6 =192× 6 = 8×144 = 1 152 households =1/52 households.
Students observe and compare these two algorithms. What are the similarities and differences?
Blackboard: 8×24×6=8×24×6.
Show me the following formula and calculate and compare.
1.
6×5×2= 16×5×2= 35×25×4=
35×25×4= 12× 125×8= 12× 125×8=
Observe the formula. Do you have the same characteristics? Are the results of two formulas equal in each row? Students calculate independently, verify their guesses and communicate with the class.
Blackboard:16× 5× 2 =16× 5× 235× 25× 4 = 35× 25× 443×125× 8 = 43×125× 8 Who can tell the laws of these formulas?
Student 1: Each formula only changes the operation order.
Student 2: The left and right formulas of each row have equal results.
Student 3: Multiply three numbers, first calculate the product of the first two numbers or the product of the last two numbers, and the value is unchanged.
Teacher: Who knows what this rule is called?
Teacher's blackboard writing: the law of multiplication and association.
Teacher: If it is represented by three numbers: A, B and C, how can this rule be expressed?
Teacher's blackboard writing: a× b× c = a× b× c
Teacher: This law is called multiplicative associative law.
Conclusion: Students, we summarized the multiplicative commutative law and multiplicative associative law together. See if the students can use it.
Second, classroom activities
1. Exercise 4 Question 1: Students finish independently, communicate with the whole class and tell the basis.
2. Connect.
Students finish independently
23× 15×2 17× 125×4 17× 125×439×25×839×25×823× 15×2
Third, the class summary
What did you learn from this class today? Is there a problem?
The second is to give full play to students' initiative, so that students can discover and understand the law of multiplication in independent exploration and cultivate their exploration ability. ]
Second lesson
course content
Page 19 ~ 2 1 in Grade Four, Example 3, Problems in Classroom Activities 1 ~ 2 and Problems 2 ~ 6 and Thinking in Exercise 4.
Teaching objectives
1. Further understand and master the law of multiplication and transformation and the law of association, and make a simple calculation by using these two operation laws.
3. Cultivate students' ability to use what they have learned flexibly to solve practical problems.
3. Let students experience the process of overcoming learning difficulties and the sense of achievement in mathematics learning under the guidance of teachers.
Emphasis and difficulty in teaching
Flexible use of multiplicative commutative law and multiplicative associative law for simple calculation.
teaching process
First, review old knowledge and introduce new lessons.
1. Recall the multiplicative commutative law and multiplicative associative law learned in the last class and describe them in your own language.
2. Fill in the blanks.
a××=b×××c=a×
We learned the law of multiplication. In this lesson, we use the law of multiplication to calculate.
Second, explore new knowledge.
Research example 3.
For example 3, calculation discussion.
6 1×25×48×9× 125
Teacher: What are the characteristics between the factors in each formula? Can we use the algorithm to make simple calculations? Students observe, think and calculate independently.
Class report, the teacher wrote on the blackboard:
1
①6 1×25×4
②6 1×25×4
③…… =6 1× 100 = 1525×4 =6 100 =6 100
2①8×9× 125
②8×9× 125
③…… =72× 125 =9× 1000 =9000 =9000
Group discussion: There are several algorithms for each problem. Which algorithm do you think is the simplest? Why? What should be paid attention to when using multiplicative commutative law and associative law for simple calculation?
The whole class communicates and reports.
The teacher summed up: the core of simple calculation using multiplication algorithm is "rounding".
It is usually possible to combine two or more numbers and multiply them to get an integer 10 or integer 100 ... Sometimes it may be necessary to decompose a number into two numbers and then combine them with other numbers to get an integer ten or an integer hundred ... In short, the calculation becomes simple.
Third, classroom activities.
1. Classroom activity questions 1: Let the students briefly talk about how to calculate and give the basis, and then finish it in the textbook.
2. Classroom activity question 2: Let students think independently first, then discuss how to do simple calculations in groups, and finally give feedback to the whole class.
Students should realize that the same calculation can have different simple calculation methods.
3. Exercise 4 Question 2: Students feedback after completing the connection independently.
4. Exercise 4 Question 7: Students give feedback after completing independently.
5. Exercise 4, question 8.
Students observe the information in the picture, then draw students' questions, and the teacher acts them out on the blackboard.
The rest of the students judge.
Finally, let the students solve at least three problems in the classroom exercise book independently.
Note: remind students to observe the characteristics of data in the formula at any time and calculate with simple methods.
Fourth, expand the practice.
Thinking: guide students to grasp the breakthrough point: 1. The number 1 ~ 9 only appears once in the formula; Second, the unit number of the product in the formula is 2.
According to these two pieces of information, it can be considered that the digits of the two factors can only be 3 and 4 respectively, and the problem can be solved by continuing analysis.
Verb (abbreviation for verb) class assignment
Exercise 4, questions 3 ~ 6.
Sixth, the class summary
What did you learn in this class? Do you have any questions?
Primary school mathematics teaching plan design II. Rational number addition teaching plan
Teaching objectives
1. Further understand the practical significance of rational number addition;
2. Experience the process of exploring the law of rational number addition and understand the law of rational number addition;
3. Feel the idea of mathematical model;
4. Develop the habit of careful calculation.
Dialogue exploration design
[Explore 1]
1. Make a profit on the first day and make a profit on the second day. Together, is it a profit or a loss?
2. Loss on the first day, loss on the second day, two days together, is it profit or loss?
3. An object moves left and right, and the right side is positive. If an object moves 5m to the left first and then 3m to the left, what is the total result after two moves?
Assuming that the origin is the starting point of the movement, use the number axis to test your answer.
Legal understanding
Article 1 of the rational number addition rule is: add two numbers with the same sign, take _ _ _ _ _ _ _ _, and put the absolute value _ _ _ _ _ _ _ _.
This rule includes two situations:
When two positive numbers of 1 are added, the positive number is obviously taken, and the absolute value is added, for example,+3++5 =+8;
2 Add two negative numbers, take the number _ _ _ _ _, and add _ _ _. For example, -3+-5 = -3+5 = -8. Answer "-8" takes the number "-"because _ _ _ _ _ _.
[practice]
1. The temperature at 6 am is -5℃, and the temperature at 5 pm is 3℃ lower than that at 6 am. What's the temperature at 5 pm?
2. The red team beat the yellow team 5-2 in the first game, and the blue team beat the yellow team 3-/kloc-0 in the second game. How many goals did the yellow team win in two games?
3. -30km northward on the first day and -40km northward on the second day. How many kilometers do you walk north in two days?
4. Imitate the format of -3+-5 = -3+5= -8:
1- 10+-30=
2- 100+-200 =
3- 188+-309=
[Exploration 2]
1. On the first day of opening, 90 yuan made a profit, and on the second day, 80 yuan made a loss. How much did you earn in two days? What should I do if I lose 120 yuan the next day?
Make a profit on the first day and lose money on the second day. Together, is it a profit or a loss?
3. When a positive number and a negative number are added, is the result positive or negative?
Legal understanding
The first half of the second rule of rational number addition is: two numbers with different signs and different absolute values are added, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
For example, +6+-2 = +6-2 = +4. The answer "+4" is marked "+"because the absolute value of _ _ _ _ _ in the two addends +6 and -2 is larger; The absolute value 4 of the answer "+4" is obtained by subtracting the smaller absolute value _ _ _ _ from the larger absolute value in the addend.
For another example, when calculating -8++3, take _ _ _ _ _ first, because the absolute value of _ _ _ _ in the two addends is larger, and then subtract _ _ _ _ from the larger absolute value to get _ _ _ _ _, so the final answer is _ _ _ _.
[discuss]
Some people say that the essence of adding positive numbers and negative numbers is to convert the addition operation into the subtraction operation of "primary school". Is he right?
[practice]
1. In the first game, the red team beat the yellow team 5:2, and in the second game, the yellow team beat the blue team 3:/kloc-0. How many goals did the yellow team win in two games?
2. If an object moves 5 meters to the right first and then -8 meters to the right, what is the total result after two moves?
3. Check the weight unit of 3 packs of washing powder: grams. If it exceeds the standard weight, it will be recorded as positive, and if it is insufficient, it will be recorded as negative. The results are as follows:
-3.5,+ 1.2,-2.7.
How much is the weight of these three packs of washing powder exceeding the standard?
4. Imitate the format of -8++3 =-8-3 = -5 to solve problems:
1-3++8=
2-5++4=
3- 100++30=
4- 100++ 109=
Legal understanding
The second half of the second rule of rational number addition is: two opposite numbers are added to get _ _ _ _ _.
For example,+3+-3 = _ _ _,-108+ 108 = _ _ _ _.
[sample learning]
P2 1。 Example 1, example 2
P22。 Exercise 2 is calculated in the format of 1.
[homework]
P29。 Exercise 1, P32. Exercise 8, 9, 10.
ersatz material
Use □ for+1 and ■ for-1. Obviously □+■=0,
1■■+□□□=■+□+■+□+ □=_____.
This shows that -2+3=+3-2= 1.
Think about it: Why is the answer yes? Why is it converted into subtraction?
2 Calculate ■■■■ +□□□□□ = _ _ _.
3 Calculate ■■■■ +□□ =■■ +□■■■ = _ _ _ _.
This shows that-5++2 =-_ _ _ _ = _ _ _ _.
4 Calculate ■■■ +□□□□□□□ =?