The first chapter is teaching content: 33 ~ 34 pages.
Activity objectives:
1. Through collecting data, operating experiments and discussing and communicating, let students experience the size of 100 million in specific situations, develop their sense of numbers and feel the close connection between mathematics and real life.
2. Get some problem-solving strategies and methods to develop students' problem-solving ability.
3. Get successful experience, and initially establish self-confidence in using mathematics to solve problems.
Focus of activities:
Let the students practice the operation by themselves, and let them actively summarize the research methods.
Activity difficulty:
Form the spatial concept of 1 100 million.
Activity preparation:
Paper, books, rice, soybeans, etc.
Activity flow:
It includes four stages: design scheme-practice-summary-expression and communication.
The first stage: establish the problem design scheme.
1. Define the purpose and requirements of the activity.
Take the group as a unit, describe it by creating realistic situations and combining specific materials.
The scale of one hundred million, from which we can understand the scale of one hundred million.
2. Establish research questions.
Example: How much is 100 million grains of rice?
How much space does 100 million students take up together?
How long does it take to calculate 100 million by mouth?
How high are 100 million coins stacked together?
How long does it take to walk 100 million meters (by car or by plane)?
How many drops of blood are there in 100 million red blood cells?
How much is a hundred million drops of water?
How many trees do you need to cut down for 100 million pairs of disposable chopsticks?
3. Make an activity plan.
(1) activity steps.
(2) Activity preparation and division of labor arrangement.
And fill in the activity steps, activity preparation and division of labor in the activity record form.
Stage 2: Hands-on Practice
Each group carries out activities as planned, and records the obtained data and calculation process in the record form. Teachers participate in student activities with targeted guidance and help.
The third stage: draw a conclusion
Students describe the scale of 100 million according to the analysis of information and data and the specific situation.
The fourth stage: expression and communication
1. Each group states the whole activity process.
2. Summary of activities.
Imagine further how big 1 100 million is.
The activity process of the evaluation team.
Notes after class.
Chapter II Teaching Objectives:
Knowledge and skill goal: with the help of things that students are familiar with, feel 1 billion from different angles and develop students' sense of numbers; The multiple ratio or normalization method can be used to help answer the question about 1 billion, and more complex data can be processed with the help of a calculator.
Process and Method Objective: Through the process of guessing, discussing and calculating, some strategies and methods to solve problems are initially obtained, and students' ability to solve problems is developed.
Emotion and attitude goal: experience the close relationship between mathematics and daily life, realize that many practical problems can be solved by mathematical methods, and realize the application value of mathematics; Willing to cooperate with others, communicate with others, and develop good quality of solving problems; Enhance environmental awareness and social responsibility.
Teaching emphasis: cultivate students' feelings about large numbers and develop their sense of numbers.
Teaching Difficulties: How to Estimate Large Numbers with Decimals
Teaching preparation:
Teacher: A multimedia courseware, balance, rice.
Student: Calculator, book, ruler.
Teaching process:
First, create scenarios and introduce topics.
1, the teacher tells you a story.
(Multimedia Demonstration): In ancient times, there was a wise minister in a kingdom who invented chess and presented it to the king. Since then, the king has been addicted to playing chess. In order to express his gratitude to the clever minister, the king promised to meet one of the minister's requirements. The minister said, Your Majesty, please put some rice grains on the chessboard. Put 1 grain rice in the 1 grid, put 2 grains of rice in the second grid, put 4 grains of rice in the third grid, and then put 8 grains, 16 grains, 32 grains, ... until the 64th grid. The king smiled: "You are so stupid, just a little bit of rice?" The minister smiled and said slowly, "Your Majesty, I'm afraid there isn't that much rice in your treasury! Forget it, I just want 28 squares of rice. Please allow me to take them home. " Students, guess, how many grains of rice are there in box 28?
2. Students guess
3. Verify Guess: Let's see who is closer to the actual situation.
Courseware demonstration: checkerboard number 1, grid 2, grid 3, grid 4, grid 5, grid 6, grid 7, grid 9, grid 10, grain (unit: grain)1248163264/kloc-. 15, 16, 17, 18, 19, 1024204840968 192 1638432768655366538+036538.
No.20 grid 2 1 No.22 grid 23 grid 24 grid 25 grid 26 grid 27 grid 28 grid 52428810485762097152419430483886081.
Teacher: So there are so many grains in the 28th box. Did you guess right?
Teacher: Let's round the rice to 100 million, and consider it as 65.438+0 billion grains.
Second, the actual operation, preliminary perception
1. Guess how many ministers will take 1 100 million grains of rice home? But what is 1 100 million grains of rice?
(blackboard writing: 1 100 million how many grains of rice are there)
Student's guess: One (several) bags of rice can fill one (several) classrooms, one (several) trucks, 1000 kg. ...
2. Designer: This is just our guess. 1 100 million grains of rice? Can you prove your guess? Think about it. How do you prove it? If the students can't answer, the teacher leads: What do we usually use to express the amount of rice? Can you find a method to calculate the quality of 654.38 billion grains of rice? Possible situations for students to express their opinions: weigh 1 100 million rice, first weigh 100 rice, then divide it by 100, then calculate the weight of 1 rice, and finally multiply it by 1 100 million rice to calculate 1 100 million rice. (or calculated according to the multiple ratio) First weigh 10g rice, then divide it by the number of grains of rice, and finally multiply it by 1 billion to calculate the weight of 1 billion grains of rice.
3. Teacher's request: Choose a scheme and calculate the quality of 654.38 billion grains of rice in groups of four. Please write out the calculation process to facilitate the later report, and you can use a calculator to help with the calculation.
4, student group calculation
5, each group reported the results, the teacher wrote on the blackboard, feeling the number of 65.438+0 billion grains of rice.
6. Extension: Teacher: Just now, we learned that 65.438 billion grains of rice weigh 2 tons (multimedia presentation). China has a population of 654.38+300 million. If everyone saves 654.38+0 grains of rice every day, the whole country can save _ _ _ _ _ _ _ _ grains of rice every day, which is equivalent to _ _ _ _ _. The student replied, Teacher: As long as everyone saves one grain of rice every day, the whole country can save so many meters. Cherish food in the future!
7. Summary method: Teacher: Just now we studied the weight of 1 100 million grains of rice. Who can tell us how to study it? Students said the teacher summed up the method:
Third, cooperative exploration and re-experience
1. Just now, we studied 100 million grains of rice. What else do you want to study about 1 100 million?
2. Students boldly imagine and ask questions. Possible situations: the thickness of 65438+ billion pieces of paper, the thickness of 65438+ billion one-dollar coins, the mass of 65438+ billion people, the length of 65438+ billion seconds ... The teacher writes on the blackboard.
3, student activities: 4 people as a study group, cooperative learning, each group arbitrarily determine a question to explore.
4. Each group reports the research results, and the teacher gives affirmation and encouragement in time.
Fourth, courseware appreciation.
How long is 1 100 million meters? The circumference of the earth's equator is 40066.449 kilometers, and 1 100 million meters is equivalent to two and a half laps around the earth. If the car travels 70 kilometers per hour, 65,438+1100,000 meters, and it will take about 2 months to travel continuously for about 1429 hours. The plane can fly 800 kilometers per hour, and it takes about 125 hours to fly continuously, as long as it takes more than five days. The spacecraft can fly 50,000 kilometers per hour, and the spacecraft of 1 100 million meters only takes 2 hours. ? How many cards are there in 654.38 billion cards? The total population of Zhejiang Province is about 50 million. If each person consumes two greeting cards every year, it needs 654.38 billion greeting cards, which is equivalent to cutting down 25,000 trees! The forest area occupied by these big trees is equivalent to our 10 campus area! "1 100 million" in the body, a normal person has an average of 75 heartbeats per minute, and 1 100 million heartbeats are the heartbeats of a normal person for about 926 days (about 2.5 years). According to statistics, there are about 65438+ billion microorganisms on the skin surface of 1 children, especially on the skin folds and fingertips. An adult has an average of 5 million red blood cells per milliliter of blood, and there are 654.38 billion red blood cells in 20 milliliters of blood (about 20 grams).
Verb (abbreviation of verb) summary and induction
1. How big is 1 billion in your mind now?
2. Who can choose a topic for today's class? (blackboard writing topic)
3. What did you get from this lesson? After thinking, students should answer their thoughts and feelings in this class in their own language (the teacher gives appropriate comments according to the students' answers).
If the students answer "I know how to estimate" and "I know through study that 654.38 billion is a big number", etc. ) Teacher's summary: In fact, there are many large numbers like 65.438 billion around us, and interested students can collect some relevant information.
Six, choose one of the three assignments:
(1) Collect numbers greater than 1 billion and related data.
(2) Collect a number greater than 1 100 million, and design your own scheme, and compare it with peers to see whose scheme can make people deeply feel how big this number is.
(3) Write an article about how big math diary is 1 billion.
Teaching reflection:
This is a math practical activity class. Learning on the basis of students' understanding and mastering the number within ten thousand consists of two parts: "understanding the number within one hundred million" and "understanding the number above one hundred million". Large numbers exist widely in life. Understanding large numbers is not only the consolidation and expansion of reading and writing numbers within ten thousand, but also one of the most basic mathematical knowledge that students must master. From the understanding of the number within 10,000 to the understanding of the number within 100 million and above 100 million, it is another expansion of the concept of student number. However, because the number 1 100 million is too large, it is difficult for students to get an intuitive feeling by combining specific quantities. Students often make mistakes when reading and writing large numbers, which is often related to the unclear concept of numbers and the lack of rich digital feelings. Therefore, after the "understanding of large numbers" unit, this comprehensive application is arranged, so that students can experience the process of guessing, experimenting, reasoning and comparing through inquiry activities, and fully feel the number of 654.38 billion by using imaginary materials.
Ask students to help them further understand the meaning of numbers and establish a sense of numbers through their perception and experience of specific numbers. Mathematics is an important subject to cultivate and develop people's thinking. In the teaching design, I strive to embody the principle of students' development, follow the students' cognitive rules, and embody the teaching principle of step by step and heuristic. Under the guidance of teachers, teaching creates scenarios, inspires students to think through the setting of open questions, learns problem-solving methods in case analysis, feels the size of the number 65.438 billion through cooperative experiments, understands and feels the application of large numbers in daily life, and cultivates students' feelings for large numbers.
(1) Create situations and cultivate a sense of numbers.
For students, large numbers are abstract. The teaching is introduced by the story of "How many grains should you get if you know more". The multimedia courseware vividly shows the change of wheat grains from less to more, and intuitively reflects the change of students' understanding of logarithm from small to large. Open-ended question "Can you guess what 65438+ billion grains of wheat are?" Then draw the students' attention to new learning activities.
(2) Connect with life and cultivate a sense of numbers.
1 100 million is too large, and it is difficult for students to have an intuitive feeling in combination with specific quantities. The thinking of primary school students is developing from concrete image thinking to abstract logical thinking. According to this feature, this problem can be solved well by contacting the things in the life of primary school students and guiding students to grasp the relative size relationship of numbers with imaginable materials in life examples and fully feeling how big the number is 65.438+0 billion. The courseware provides rich materials in the form of words and pictures from five aspects: data, length data, area data, time data and weight data. Such concrete materials are closely related to students, which makes them form vivid representations. When they encounter similar situations, a concrete reference appears in their minds. At the same time, these materials are the introduction of comprehensive knowledge and the infiltration of students' love for the motherland and hometown education. This kind of teaching makes students feel the close connection between mathematics and real life, which not only cultivates students' feelings of loving mathematics and life, but also develops students' sense of numbers.
(3) Group cooperation, strengthening communication, number sense is a highly selective spiritual feeling, which is inextricably linked with students' personality. In the same mathematical situation, some students are witty, while others digress. These performances are directed at personal mathematical temperament. Discuss, do, write and comment ... "Wisdom is at your fingertips", "Inspiration comes from thinking collision", action communication, language communication. The form of cooperative division of labor allows students to communicate freely and fully in group cooperation. In the communication, * * * is inspired and * * is also making progress.