? Is the quotient of one digit divided by two digits two digits? Pen division of 1
Teaching content:
People's Education Edition Volume VI P 19? P20 case 1, case 2 and? Do it.
Teaching objectives:
1. On the basis of understanding arithmetic, students can learn the written calculation method of dividing one digit by two digits and making the quotient two digits.
2. Further cultivate students' computing ability, hands-on operation ability and preliminary generalization ability.
Teaching focus:
One digit divided by two digits, quotient is a written calculation method of two digits.
Teaching difficulties:
Let students understand arithmetic and master the calculation format of division formula.
Teaching aid preparation:
Dictation cards, projectors, sticks
Teaching process:
Teacher-student activities
First, exchange old knowledge and establish contacts.
1. Oral calculation
600? 6 27? 3 240? 8 160? four
Manual calculation
____ _____
3)9 9)37
Second, create scenarios and introduce new lessons.
1. Show the map of planting trees at P 19, and ask the students to explain the meaning.
2. Guided observation: What information does the picture tell us? What questions can be asked based on this information? How to form? (According to the students' answers, the teacher acts it out.)
42? 2 52? 2
3. teacher: 42? How much is 2 (student: 42? 2=2 1)
what do you think?
(health: 40? 2=20 2? 2= 1 20+ 1=2 1)
Students can work out the answer with their mouths, so how to do it vertically? Blackboard: One digit divided by two digits.
Third, explore and understand the algorithm independently.
1. Teaching examples 1 42? 2=2 1
(1) vertical calculation, will it? Give it a try.
Students give feedback after independent calculation.
The first and the second
2 1 2 1
2)42 2)42
42 4
0 2
2
(2) By comparison, which algorithm do you like? Tell me why.
Students express their opinions: (most students like one algorithm, which is simple and short vertically, and few students like the second one, which is in the form of textbook examples)
Teacher: Actually, the second method has its own advantages. You can see the calculation process clearly.
(3) The teacher explained while demonstrating with a computer: the calculation order of the pen division is the same as that of the oral calculation, and the division should start from the highest dividend.
Please explain it to the person who did it in the second way.
(Teacher's cooperation and supplement)
(4) Let students ask questions
(Some students will also put forward the first vertical pose to clearly see the calculation process. )
Teacher: Now, please use your favorite method to calculate 52 vertically? 2
2. Teaching Example 2:
52? 2
(1) Students give feedback after independent calculation.
A first type 26 and a second type 26
2)52 2)52
52 4
0 12
12
(2) Which algorithm do you agree with?
After discussion, the students come to the conclusion that the first method is to calculate 26 orally, and the second method should be correct.
(3) Teacher: We use sticks to verify (the teacher and students put sticks together, and the teacher explains while demonstrating).
52? In other words, divide 52 pieces (5 bundles of 2 pieces) into 2 pieces on average.
First, divide the 5 bundles into 2 parts, each part has 2 bundles (20), and the rest 1 bundle; Then unpack the extra 1 bundle into two, that is, 12, and divide it into two parts, each part is 6, which adds up to 26, so 52? 2=26
The teacher refers to the second vertical position, divided by the remaining dozens. 1? How did this 1 come from? What does this mean?
Refers to the business position? 6? How did you get this 6? Talk to each other at the same table.
(4) Let's see how the computer calculates. (Computer demonstration) Who wants to be a little teacher and tell you about the process of computer calculus? (Ask students to describe the calculation process)
(5) Compare the difference between Example 1 and Example 2, and emphasize that there is a remainder after division with a pen. What should I do? What is the connection between remainder and divisor?
(6) Guiding reading problems
3. Practice feedback P20 to achieve 1
4. Introduction summary: From which one? How to write business? What if there is a remainder after division by dozens of digits? What is the relationship between remainder and divisor divided by each time?
Fourth, apply new knowledge to solve problems.
1. Complete the following division formula.
1 □ □□
4)4 8 6)8 4
4 □
□ □□
□ □□
0 0
2. Competition, who can calculate accurately and quickly?
P20 Do One and Do Two.
Please be a little doctor, make a diagnosis first, and then what? Treat a disease? .
34 1 1 1
2)68 6)96 5)60
68 6 5
0 6 1
six
Verb (abbreviation of verb) class summary
Blackboard design:
The quotient of one digit divided by two digits.
Example 1 42? 2=2 1 example 2 52? 2=26
2 1 26
2)42 2)52
4 4
2 12
2 12
0 0
Divider is an estimate of the division of a digit 2.
Teaching content:
Compulsory Education Curriculum Standard Experimental Textbook Grade Three Volume II Page 16 Example 2 and? Do it. Exercise 3, questions 3 and 4.
Teaching objectives:
1, make students realize the necessity of learning division estimation and understand that divisor is a general method of division estimation of one digit.
2. Guide students to make reasonable estimates according to specific conditions, and cultivate students' good thinking quality and mathematical application ability.
Teaching process:
First, create situations and lead to problems.
1, textbook example 2: Uncle Li, how many boxes did the three of them transport on average?
2 Li Sijia's electricity consumption for four months is 143 kwh. What is the average monthly electricity consumption?
Second, think independently and solve problems.
1, formula: 124? 3? 153? 4?
2. Let the students say the meaning of the formula.
3 learning estimation methods.
( 1) 124? 3? How to estimate?
Health 1: 124? 120 120? 3=40 124? 3? 40
Health 2:124 =120+4120? 3=40 4? 3? 1 40+ 1=4 1
Analysis and comparison: Both methods are correct. Although there are some differences, they are all close to the exact values, which will not affect the reasonable solution of the problem.
(2) Students' independent estimation: 143? 4?
Health 1: 143? 160 160? 4=40 143? 4? 40
Health 2: 143? 120 120? 4=30 143? 4? 30
Guiding students to induce divisor is a general method to estimate one-digit division: treat divisor as a whole hundred (integer ten) or several hundred (thousand and hundred) numbers, keep the divisor unchanged, and calculate it by the basic method of oral calculation.
Third, estimate according to the actual situation.
1.How many notebooks can 3 yuan and 200 yuan buy at most?
2./kloc-where is the tour group for 0/85 people? Sunshine Hotel? Accommodation, one room for every 4 people, how many rooms do you need at least?
Question 1:
(1) Student autonomy is estimated at 200? 3? _____。
Health 1: 200? 2 10 2 10? 3=70 200? 3? 70 can buy 70 copies at most.
2: 200? 180 180? 3=60 200? 3? You can buy 60 copies at most.
3: 200 = 180+20 180? 3=60 20? 3? 660+6=6 6 You can buy up to 66 copies.
(2) Organize students to discuss: Which answer do you think is appropriate? Can 200 yuan be estimated as 2 10 yuan? Why?
(3) Organize student exchanges: 200 yuan can estimate 200, but actually it is only 200.
Question 2:
(1) Formulated estimation of students' independence.
185? 4?
Health 1: 185? 200 200? 4=50 185? 4? 50. At least 50 rooms are needed.
Health 2: 185? 160 160? 4=40 185? 4? 40. At least 40 rooms are needed.
(2) Organize students to discuss: Which answer do you think is appropriate? 185 can be estimated as 160 yuan? Why?
(3) Organize student exchange: It is known that 185 people need accommodation. When considering the number of rooms required, 185 should be regarded as 200, so as to ensure that there are enough rooms.
Fourth, guide students to tell examples of division estimation in life.