Teaching materials and academic analysis: This unit is taught on the basis that students have become more proficient in calculating the addition and subtraction of two-digit numbers within 100. This part of the content includes: three-digit numbers Add two or three digits without carry, add with carry, continuous addition and estimate (the sum is within 1000). Textbooks create situations during teaching so that students can further experience the connection between mathematics and life in the process of solving simple practical problems, enhance their awareness of applied mathematics, and generate positive emotions towards mathematics.
Teaching objectives: To enable students to connect with their experience in calculating addition within a hundred, and to explore and understand the written calculation of three-digit numbers
Teaching focus: to enable students to experience the exploration of adding two and three-digit numbers to three-digit numbers In the process of numerical calculation, he can write and add three-digit numbers within 1000, and he can use vertical calculation to calculate relatively simple continuous addition problems.
Teaching difficulties: Enhance the awareness and ability of estimation, and be able to estimate based on specific situations.
Teaching hours: nine hours
Add without carry in the first lesson
Teaching content: Examples on page 31 of the textbook, think about it on page 32, do it 1 —4 questions.
Teaching requirements:
1. Let students experience the process of exploring the addition of three-digit numbers to two or three-digit numbers without carry and the verification method of addition
.
2． Students understand the role of verification. .
3. In the process of exploring algorithms, students can experience the close connection between mathematics and life, enhance their interest in mathematics learning, and develop mathematical thinking.
Teaching focus:
Students experience the process of exploring the addition of three-digit numbers to two or three-digit numbers without carry and the verification method of addition.
Teaching difficulties: Students experience the process of exploring the verification method of addition.
Teaching process:
1. Conversation introduction
1. Children, have you ever written a diary? Today, the teacher brings you a mathematics diary. Do you want to read it?
(Show the blackboard)
1. Classmates, what do you think after looking at the blackboard? Have any math questions?
(Students ask questions by name, and teachers organize them)
1) How many books are borrowed by the first graders and second graders?
2) How many books will the second and third graders borrow?
3) How many books will the first and third grade students borrow?
4) How many books will the second graders and sixth graders borrow?
Conversation: Just now, the students asked a lot of math questions. They are really children who love to use their brains. Can you solve these problems?
2. Learning new lessons
1. Sample questions:
How many books will the second and third graders borrow?
(Referring to the nominal column formula: 143 126)
Question: Let’s ask students to give it a try and see if they can get the result.
(Student exercises, group discussions and exchanges)
2. Teacher: Who is willing to tell everyone the calculation method you came up with?
(Named)
Teacher: Students, think about it, what should you pay attention to during the calculation process?
3. Encourage students to use written calculations.
1) Question: What to do with two addends when making vertical expressions? How to calculate?
2) Question: Which one should be counted starting from?
Teacher’s vertical calculation:
One hundred and ten
1 4 3
＋ 1 2 6
2 6 9
3) Discuss the written calculation process by name, and what does each digit in the result mean?
4) Summary: How should we form the vertical expression when adding three digits, and where should we start counting?
4. Teaching verification method.
1) Introduction: Check whether the calculation is correct and check the calculation.
(Written on the blackboard: Calculation check)
2) How to exchange the positions of the two addends in the example problem, how to formulate the formula?
(Vertical writing on the blackboard: 1 2 6)
＋ 1 4 3
3) Students do calculations in writing and see how the calculation results compare with the examples?
4) Note: In pen arithmetic, you need to check whether the addition is done correctly. You can calculate it again by exchanging the positions of the addends to see if the numbers are the same. This kind of check is called verification.
5． Summary: In this lesson, we learned three-digit pen arithmetic addition. How should we form the vertical expression? From which digit to start: and how to check?
3. Consolidation exercises
1. Think about question 1.
1) Do the math in the book. (Students calculate independently)
2) How do you want to check the calculation?
3) Report. How do you calculate it? How is it verified?
1. Think about it and do question 3
1) First, tell me what do you know from the table?
2) Independent calculation.
3) Report.
3. Think about it and do question 4
1) Explain the meaning of the picture.
2) Independent calculation.
3) Report.
Four. Classwork
Think about question 2
Calculate independently. Pay attention to aligning the numbers.
Blackboard design:
Add without carry
143 126
One hundred and ten
1 4 3
＋ 1 2 6
2 6 9
Verification:
1 2 6
＋ 1 4 3
2 6 9
Teaching reflection:
In the second lesson, solve the practical problem of finding the number that is more (or less) than a number
Teaching content: Sample questions on page 33 of the textbook, think about questions 1-4 on page 34.
Teaching objectives: To enable students to initially learn to solve practical problems of finding a number that is more (or less) than a number, and to initially develop students' analysis, comparison and reasoning abilities.
Teaching preparation: 33 red flower pieces
Teaching process:
1. Review
Use "more than...", Say a sentence "less than..." or "bigger than..." or "smaller than...". Tell me who has more and who has less?
2. New Grants
1. Situation introduction:
The students arranged flower pieces and played games. Xiaoying (the girl in the middle) placed 11 red flower pieces, and Xiaohua (the boy on the left) wanted to place 3 more red flower pieces than Honghong. How many flower pieces do you think Xiaohua should place?
(1) Ask students to place them in a row.
(2) Question: How many red flower pieces do you think Xiaohua should place? How do you arrange them? If you use arithmetic, how should it be expressed? (Write on the blackboard: 11 3 = 14 (pieces))
(3) According to the formula, tell us why we need to use addition to calculate?
Tell us the meanings of 11, 3, and 14 in the formula.
Summary: To find out how many red flower pieces Xiaohua should place, just add the same number of red flower pieces as Xiaoying’s and add 3 more than Xiaoying’s, and you can find out how many red flower pieces Xiaohua should put. The number of pendulums, so when you encounter a number that is more than one number, you need to use addition calculations.
(4) Clapping game, consolidation:
①The teacher clapped 2 times, the students clapped 3 times more than the teacher, how many times did the students clapped?
②The teacher clapped his hands 6 times, and the students clapped 2 times more than the teacher. How many times did the students clapped?
Group practice, and after each time, ask the students to list the corresponding calculations orally.
Free practice with the same seat.
2． Here is a sample question: Xiaoping also plays the flower arranging game with them. Xiaoping wants to place 3 fewer flower tiles than Xiaoying does.
(1) Question: How many red flower pieces do you think Xiaoping should place and why? Discuss in groups. You can use the method of placing school tools or other methods.
(2) Report on the group activities:
Question: How can it be represented by an equation? [Write on the blackboard: 11-3=8 (pieces)]
Why do we need to calculate by subtraction?
Summary: To ask how many pendulums Xiaoping should place, just remove the part that is more than Xiaoping from the red flower pieces placed by Xiaoying, which is the number of small pendulums, that is, the ratio is 11 Which number is less than 3? Use subtraction to calculate.
3. Summary: Just now we helped Xiaohua and Xiaoping calculate how many red flower pieces they each placed. Now ask the children to think about it, what are the differences in the calculation methods of these two questions? Share your ideas with the group members
for a listen. (After the group discussion, a representative will speak.)
4. Clapping game to consolidate:
(1) The teacher claps 5 times, and the students clap 2 times less than the teacher. How many times do the students clap?
(2) The teacher claps 9 times, The number of times the student clicked was 6 less than the teacher. How many times did the student click?
Group practice, and after each session, ask the students to list the corresponding calculations orally.
Free practice with the same seat.
3. Consolidation exercises
1. Complete and think about question 1.
(1) Students look at the picture and describe the meaning of the picture completely orally.
Question: Who walked more? How did you know?
(2) Students answer the questions independently and talk about their solutions and ideas.
(3) Reminder, after solving this problem, generally write the appropriate unit name after the number.
2． Complete and think about questions 2 and 3.
After students read the question, they will state the meaning of the question orally.
After students solve the equation, they will talk about their problem-solving ideas.
4. Class Summary
Today, we used the knowledge we learned before to solve practical problems about numbers that are more (or less) than one number. In the process of solving the problem, you need to figure out who is more and who is less, and then choose the correct method to solve it.
5. Homework
Think about question 4. (Vertical calculation)
Teaching postscript:
Third lesson exercises
Teaching content: Questions 1-5 of Exercise 4 on page 35 of the textbook.
Teaching objectives:
1. This enables students to further consolidate the method of calculating three-digit numbers using vertical calculations without carrying, and become more proficient in calculations.
2． This enables students to further improve their analysis and reasoning abilities and to correctly solve practical problems of finding a number that is more (or less) than a number.
Teaching process:
1. Reveal the topic
2. Oral calculation. And use "more (less) than..." to explain the meaning of each equation.
23 15 64 35 100-70 76-26
56-9 96 - 53 62 26 50 30
1. Complete questions 2 and 3 of Exercise 4.
(1) Ask students to fully describe the topic.
(2) Complete it independently and explain why addition (or subtraction) is used to solve the problem.
2. Complete Question 4 of Exercise 4.
(1) Students understand the meaning of the question.
Question: What does "22 yuan more expensive" mean? What does "at least bring dozens of yuan" mean?
(2) Students estimate that if some students say it through oral calculation, If you want to bring 68 yuan, you need to guide him to make an estimate.
3. Complete exercise 4, question 5.
(1) Students discuss and remind them to pay attention to "most" and "least".
(2) Tell me what you think.
4. Problem-solving exercises
1. Supplement: (1) The Young Pioneers planted 36 poplar trees, and the number of sycamore trees planted was 20 more than the poplar trees. How many sycamore trees were planted?
(2) The Young Pioneers planted 56 sycamore trees. . The number of poplar trees planted is 36 less than that of sycamore trees. How many poplar trees were planted?
① Students read the questions and complete them independently.
② Please tell us your solution to each question.
2． Show: (1) There are 16 peacocks in the zoo. There are 3 more orioles than peacocks?
(2) There are 38 people in the school calligraphy group and 6 less people in the art group than the calligraphy group. _________?
① Ask students to ask appropriate questions and talk about why they ask this question.
②Students’ answers.
5. Summary of the whole lesson
When answering questions about how many numbers are more (or less) than one number, you must first figure out who is more and who is less, and understand After knowing it, choose the correct method to answer it.
6. Homework Exercise 4 Question 1.
Teaching postscript:
Lesson 4 Carry Addition
Teaching content: Sample questions on pages 36-37 of the textbook, think about and do questions 1-4.
Teaching requirements:
1. Enable students to explore the written calculation method of adding three-digit numbers to two or three-digit numbers in the process of solving problems.
2． In the process of exploring algorithms, students can experience the close connection between mathematics and life, enhance their interest in mathematics learning, and develop mathematical thinking.
Teaching focus: Explore the written arithmetic method of adding three-digit numbers to two or three-digit numbers with carry.
Teaching difficulties: Understand the close connection between mathematics and life, enhance interest in mathematics learning, and develop mathematical thinking.
Teaching process:
1. Review preparation
1. Oral calculation.
4 6 50 90 60 90
8 3 70 80 3 7
Question: What kind of addition are these questions? What is the sum of each question and the highest digit? Why are they all 1?
2． written calculation. 37 25 64 8
Question: How are these two questions added in written calculations?
1． Introducing a new lesson: When adding with carry within a hundred, you must first align the same digits and add them from the ones digit. When the ones digit reaches ten, add one to the tens place. In this lesson, we will use this knowledge to learn carry with a calculation within ten thousand. addition.
(Blackboard topic: Carry addition)
2. New teaching
Example question pictures and study examples.
1． Present question 1: How many books will the first and second grade students borrow?
1) Refers to the nominal formula: 85 143=
2) Students try written calculations.
3) Name the calculation method.
Q: From whom? Let’s talk about the process of adding units.
Question: What is the result of adding 8 to 4 in the tens place? What should I do if the number of tens is full? How to write the sum in the tens place?
Question: How much does it add up to the hundreds place? Why 2?
4) Name the student to describe the complete oral and written calculation process.
5) Ask students to check the calculations in the book and then fill in the horizontal numbers.
2． Present question 2: How many books will the first and third grade students borrow?
1) Name the formula: 85 126=
2) Ask students to independently explore and solve the problem and perform it on the name board.
3) Check collectively and talk about what should be paid attention to when calculating?
4) Students check calculations independently and write the numbers in the horizontal form.
1． Summary
1) Please think about it, how do you calculate additions within ten thousand?
(Organize student discussions)
2) Organize students to communicate.
3) Summary: When doing pen arithmetic addition, the same digits must be aligned; starting from the ones digit, which digit adds up to ten, and the previous digit must be advanced by one.
Three Consolidation Exercises
1. Think about question 1.
1) Do the math in the book.
2) Report. How do you calculate it?
2． Think about it and do question 3
1) First find out where the mistake is and then correct it.
6 5 7 6 3 3 4
+2 4 3 +6 4 6 +5 6 9
2 0 8 7 1 2 8 9 3
2) Report.
3. Think about it and do question 4
1) Explain the meaning of the picture.
2) How to list the formula?
3) Independent calculation.
4) Report.
4． Think about question 2
1) Calculate independently. Pay attention to aligning the numbers.
2) How did you check the calculation?
Four. Summary
What did you learn in this lesson? How to calculate three-digit addition by pen?
Blackboard writing design:
Carry addition
85 143= 85 126=
8 5 8 5
+1 4 3 +1 2 6
2 0 8 2 1 1
Teaching reflection:
Consolidation exercises in the fifth lesson
Teaching content : Exercise 5 on page 38 of the textbook.
Teaching requirements:
1. To enable students to further master the written calculation method of adding three-digit numbers to two- and three-digit numbers with carry.
2． In the process of exploring algorithms, students can experience the close connection between mathematics and life, enhance their interest in mathematics learning, and develop mathematical thinking.
Teaching focus: Students further master the written calculation method of adding three-digit numbers to two- and three-digit numbers with carry.
Teaching difficulties: In the process of exploring algorithms, realize the close connection between mathematics and life, enhance interest in mathematics learning, and develop mathematical thinking.
Teaching process:
1. Revealing the question
A child named Xiao Ming has encountered a problem. Are you willing to help him? He doesn’t know how to add three-digit numbers in writing. Who will tell him? (Student answer) What should he do if he wants to do three-digit addition skillfully?
Today, we will take him to practice related calculations.
2. Calculation exercises
1. Question 1 of Exercise 5: Compare and do the calculations.
6+8 7+9 6+3 5+7
680 790 630 570
1) Students do their own calculations.
2) Tell your deskmate, how did you calculate the questions in the second row?
3) Compare: What are the similarities in each set of questions? What are the differences?
4) Point out: When calculating, any number in which digit adds up to ten must be moved forward one digit.
2． Think about question 2
1) Calculate independently. 2) Report.
3. Exercise 5 Question 4.
1) Read the question. 2) How to get from the pavilion to the vineyard? How many roads are there? Which way is closer? Talk to your deskmate. Speaking by name
3) The tablemates said to each other: From the pavilion to the plum garden? Which way is closer? Say it by name.
4) Is it closer from the pavilion to the vineyard or to the plum garden?
Tip: To compare which one is closest, usually compare the nearest roads.
4． Exercise 5, Question 5
1) Explain the meaning of the picture. 2) How many times did Xiao Ming jump in one ***? What do you think? Where is Xiaofang? What do you think? Question:
How to list the formula? 3) Independent calculation. 4) Report.
3. Class Summary
What should you pay attention to when calculating addition without carry?
Four. Homework: Question 3 of Exercise 5.
Teaching postscript:
Continuous addition in the sixth lesson
Teaching content: Example questions on pages 39-40 of the textbook, think about questions 1~3
Teaching requirements:
1. Enable students to explore the calculation method of adding three numbers in the process of solving problems, and encourage the diversification of algorithms.
2． Use the knowledge you have learned to solve some practical problems.
3. In the process of exploring algorithms, students can experience the close connection between mathematics and life through communication and comparison, enhance their interest in mathematics learning, and develop mathematical thinking.
Teaching focus: enable students to explore the calculation method of adding three numbers together in the process of solving problems, and encourage the diversification of algorithms.
Teaching difficulties: Use the knowledge you have learned to solve some practical problems.
Teaching process:
1. Review
Talk: The teacher is going to test your first-grade knowledge today. Are you confident?
1. Oral calculation. 8 5 1 6 7 3 9 8 2 6 5 3 9 7 3 7 8 6
2. Find the fastest and best way to verbally calculate the sum of the numbers in each triangle.
4 3 9
5 5 7 5 8 1
Q: How to calculate it more easily?
3. Question reveal: Today we will further study how to calculate the consecutive addition of three numbers. (Written on the blackboard: Lian Jia)
2. New grant
1. Teaching examples.
An example question: How many books does the first, second and third grade student borrow?
1) How do you plan to formulate the formula? (Speak by name) The teacher writes on the blackboard: 85＋143＋126
2) Tell your classmates, how do you plan to calculate? (The deskmate said, and then calculated independently) Name and tell how to calculate.
3) Think about it, are there any other ways? Student group discussion.
4) Name: You can also list only one vertical formula: 8 5
1 4 3
+ 1 2 6
3 5 4
5) What method do you like to use for calculation? Talk in a group of four. Let students realize that it is simpler to "just list one vertical form".
2． Give it a try in teaching: How many books will the fourth, fifth and sixth graders borrow? How to list the formula? (Name theory)
178＋194+236
1 7 8
1 9 4
＋ 2 3 6
□□□
Which two numbers are more convenient to add first to the ones digit? What about the top ten? Discussion at the same table.
If the numbers on which digit add up to tens, add the number to the previous digit. (Students complete the calculations themselves)
1. Consolidation exercises
1. Think about question 1.
1) Independent calculation. Tip: Is it right to want to do it all? Then you have to calculate it very carefully and carefully!
5 3 2 7 9 5 8 6
3 1 6 4 0 2 1 1 7
＋1 2 5 +3 1 1 ＋2 0 8
What should I do if I’m done and want to know if it’s right? (Calculation required) Generally, the method of calculating again is used for verification.
2) Tell your deskmate how you calculate.
3) Report by name and check collectively.
3. Think about it and do question 3
1) Name the person and state the meaning of the picture. 2) How many trees can three classes plant per day? How to formulate equations
3) Students calculate independently. 4) Report and check.
5． Think about question 2.
Students complete independently.
2. Class summary
What did you gain today?
Blackboard design:
Lianjia
How many books can the first, second and third grade students borrow?
85＋143＋126=354 (this edition)
8 5
1 4 3
+ 1 2 6
3 5 4
Teaching postscript:
Addition estimation in the seventh lesson
Teaching content: Examples on pages 40-41 of the textbook, give it a try and think about it Do questions 1~4
Teaching requirements:
1. Enable students to understand estimation methods in the process of solving real-life problems.
2． In the process of exploring algorithms, students can develop their estimation awareness and ability, and experience the close connection between mathematics and life.
Teaching focus: Cultivate students’ estimation awareness and estimation ability.
Teaching difficulties: enable students to understand estimation methods in the process of solving practical problems in life.
Teaching process:
1. Revealing the problem and introducing new lessons
Yesterday, the teacher went to buy a mobile phone and liked one. The price was 896 yuan. How to pay more conveniently?
1. Let’s talk about how close each of the following numbers is to hundreds.
896 401 608 597 888
2. Revealing the topic: In this lesson we will use this knowledge to learn new knowledge.
(Blackboard topic: addition estimation)
2. New Professor
The teacher walked around the mall again and saw these products.
1. Teaching example: Show product advertisements.
1) Please tell me what products are available? What are the prices?
2) Can you tell me how much each item costs? (My deskmate said it)
The teacher said it by name.
3) Estimate how many hundred yuan it will cost to buy a telephone and a rice cooker?
4) What do you think? Talk in a group of four.
5) Name theory.
6) Where did the 200 come from? (Discuss at the same table. Say by name.)
7) Guidance statement: 98 yuan is close to 100 yuan, and 192 yuan is close to 200 yuan. 100 200=300 (yuan), it takes about 300 yuan.
2． Try teaching: How many hundred yuan does it cost to buy a bicycle and an electric fan?
1) What do you think? Talk to your deskmate.
2) Name the person and emphasize the reasons.
3) Question: What two things do you want to buy? Estimated to be a few hundred yuan?
4) Students should think independently before talking to their deskmates. Reminder: In order to make it easier for you to remember which two things you bought when communicating with the whole class later, it is best to write them down in notes.
5) Naming and collective judgment.
3. Summary: When we make an estimate, we generally treat a number as an integer that is close to it, and then perform calculations. The result obtained is an approximate number.
3. Consolidation exercises
1. Think about it and do question 1
1) Show the question: Do you know how many hundreds each number is close to?
503, 492, 207, 813, 589, 904, 296, 407, 399, 602
2) Talk to your deskmate. 3) Report by name.
2． Think about it and do the question 2
1) Students think independently and do the question.
2) Report by name. Tell me what you think?
3. Think about question 3
1) Name the estimated results. What do you think? 2) Teacher summary: Treat each addend as a whole hundred, and then estimate the result. 3) Students are calculated independently. 4) Report by name.
4. Think about question 4
1) Students read the question independently. 2) Thinking: Under what circumstances is it enough to sit? When is it not enough to sit?
3) Let us estimate how many people there are? (400 people) What does it mean that there are about 400 people? (Maybe more than 400, maybe less than 400)
4) Is it more or less than 400? How can you tell? (Both 195 and 198 are less than 200, so the sum is less than 400.
)
1. Class Summary
What did you learn today? What should you pay attention to when estimating?
Teaching postscript:
Eighth Lesson Exercise (1)
Teaching content: Questions 1-5 of Exercise 6 on page 42 of the textbook
Teaching requirements: enable students to further master the carry addition of three-digit numbers plus two or three-digit numbers and the written calculation method of continuous addition, and have a complete understanding of addition within a thousand. Enable students to develop the habit of checking, consciously make estimates, and use the knowledge and methods they have learned to solve simple practical problems.
Teaching focus: To enable students to further master the written calculation methods of three-digit carry addition and continuous addition.
Teaching difficulty: Be able to accurately calculate three-digit numbers and two- and three-digit carry additions in writing.
Teaching process:
1. Unveil the question
Do you like to go to the park with your parents? Today we invite Mr. Eggplant and Teacher Pod to go to the park. Are you willing? Walking with them, we must be prepared to solve the problems they raise. Are we confident? Let’s go! Look, what happened? You have to answer the questions on the door before you can enter. (Show the blackboard: There is a door in the picture, and inside the door is written: Tell me how many hundreds each number below. 204 598 499 305)
2. Practice of written addition
1. Exercise 6 Question 2
Conversation: There are beautiful butterflies in the park. They are flying around happily. Which flower do they fly to?
1) Students complete the exercises independently. 2) Report by name: Which flower should each butterfly fly to?
1. Exercise 6, Question 3.
At this time, a little bird flew to us and asked us: What are the approximate numbers of these calculations? Can you help me calculate it in vertical form? Who will help it?
1) First estimate it to be about a few hundred. Tell me how you estimated it?
2) Independently use vertical calculation. (Named board performance) Check collectively.
3) Tell me by name how you checked the calculation? What to check?
(When checking, you should check whether the calculation results are consistent with the vertical results, and whether the numbers are copied correctly.)
2. Exercise 6 Question 4
There are many children in the park. What are they doing? How many people are there?
1) Students read the questions to themselves and understand the meaning of the questions.
2) Question: What does "total" mean? (How many people participate in the activity in a day.)
3) Students calculate independently. 4) Report and check.
4. Exercise 6, Question 5
1) Name the person and state the meaning of the picture.
2) Teacher summary: Each side of the flower bed is 268 centimeters. The three sides of the triangular flower bed are the same length. How many centimeters is the railing of the flower bed? What do you think? (Three 268s add up.)
3) Students calculate independently 4) Report and check.
3. Assignment
Question 1 of Exercise 6: Calculate continuous addition in vertical form.
Teaching postscript:
Review of the ninth lesson (1)
Teaching content: Review of questions 1-5 on pages 43-44 of the textbook
Teaching requirements: 1. To enable students to further master the carry addition and continuous addition of three-digit numbers and two- and three-digit numbers, and have a complete understanding of addition within a thousand.
2． Enable students to develop the habit of checking, consciously make estimates, and use the knowledge and methods they have learned to solve simple practical problems.
Teaching focus: To enable students to further master the oral arithmetic, written arithmetic, estimation, and written arithmetic methods of three-digit plus two-digit carry addition.
Teaching difficulties: Be able to accurately perform written calculations of three-digit numbers plus two- and three-digit numbers, carry addition and continuous addition.
Teaching process:
1. Question reveal: What knowledge have we learned these days? Let's see who can calculate faster and better today. (Topic)
2. Calculation exercises
1. Review question 1. 1) Show oral arithmetic problems.
60＋90 80－40 50＋60 70 80 40＋70 90 30 60 70 50 90
2) Students calculate independently. 3) Report and check. 4) Tell me how you calculated it?
2． Review question 2.
1) Read the questions by name and clarify the meaning of the questions.
Independently use vertical calculations and check the calculations. (Named board performance)
2) Report by name and check collectively.
1) Tell me by name how you checked the calculation? What to check?
(When checking, you should check whether the calculation results are consistent with the vertical results, and whether the numbers are copied correctly.)
3. Review question 3
1) First estimate the number to be about several hundred, one after another.
2) Calculate independently, and then talk to each other at the same table.
3) Report. Tell me what to pay attention to?
4) Summary: When estimating, we should regard these addends as close to the whole hundred, and then add them. The result is not a specific number.
4. Review question 4
1) Name the person and explain the meaning of the picture.
2) Students calculate independently. report.
5． Review question 5
1) Name the person and explain the meaning of the picture.
2) Question: What does "the number of people going to the third grade as many as the first grade" mean? .
3) Students should complete it independently. Requirements: First estimate how many people went to the three grades in one ***, and then calculate whether your estimate is correct.
3. Class summary
Teaching postscript:
Review of the tenth lesson (2)
Teaching content: Review of questions 6-10 on pages 43-44 of the textbook
p>
Teaching requirements: 1. In the process of analyzing and solving the practical problem of "finding how many more (or less) numbers than a number", we will further deepen our understanding of the meaning of addition and subtraction operations, realize the close connection between mathematics and life, and accumulate the knowledge to solve simple problems. Experience with practical problems.
2． Enable students to develop the habit of checking, consciously make estimates, and use the knowledge and methods they have learned to solve simple practical problems.
Teaching focus: Analyze and answer the practical problem of "finding the number that is more (or less) than a number".
Teaching difficulty: be able to accurately find out the quantitative relationship of simple practical problems such as "finding the number that is more (less) than a number".
Teaching process:
1. Revealing the question: In this lesson we will continue to review the knowledge about addition of numbers within a thousand. (Blackboard writing topic)
6. Review question 6 1) Show: Do the math and compare, what did you find?
346+113 552+175
346+213 452+275
346+313 352+375
p>2) Name the students to talk about.
The teacher guide asked: How did the second addend in the first group change? What about the first addend and the second addend in the second set? Do you think their results will change? Are there any rules?
3) Students calculate to verify their conjectures. 4) Students report results and verify.
5) Summary.
The first group: the first addend remains unchanged, the second addend increases by 100 for each question compared to the previous question, and the sum also increases by 100 accordingly.
Second Group: The first addend in each question is 100 less than the previous question, and the second addend in each question is 100 more than the previous question, and the sum remains unchanged.
3. Problem-solving exercises
1. Review question 7
1) Students read the question to themselves. 2) Question: "How many meters of cable will be used in the afternoon?" What do you think?
3) Name the person and share your thoughts. Students are calculated independently.
2． Review question 8
1) Explain the meaning of the picture. 2) Independent calculation. report.
3. Review question 9
1) Explain the meaning of the picture. 2) Independent calculation. 3) Report.
Let’s talk about the conditions used in these two questions.
4. Review question 10
1) Discuss in the group: Among each set of numbers below, which number do you think is the most special? Why?
2) Name theory.
3. Class summary.
Is that possible? Please adopt it if it helps you