Teaching objectives
1. Know the counting units "ten thousand", "one hundred thousand", "one million", "ten million" and "one hundred million", master the numerical sequence table, and know the decimal relationship between two adjacent counting units within one hundred million.
2. Understand the reading method of multi-digits. Under specific circumstances, we can correctly read the numbers within 100 million according to several levels, and understand and explain the reading of multi-digits.
3. In the process of understanding numbers, combined with realistic materials, let students feel the meaning of numbers within 100 million, cultivate their sense of numbers, and experience the close relationship between mathematics and life. Cultivate team spirit through cooperation and communication.
Emphasis and difficulty in teaching
Teaching emphasis: Know the counting units of "ten thousand", "one hundred thousand", "one million", "ten million" and "one hundred million" and be able to read multiple numbers correctly.
Teaching difficulties: feel the size of the counting unit and understand the reading of multiple digits. And decimal relation
teaching tool
courseware
teaching process
First, create situations and introduce new lessons.
Students, we have learned numbers within 10,000. In daily life and production, we often use numbers greater than 10,000. (Showing the data of the fifth national census in China in 2000)
Can you read these data? If a classmate raises his hand to read, please ask two or three students to try to read, and the teacher will not judge whether they read correctly. (blackboard title: understanding numbers within 100 million) today, let's learn about numbers within 100 million. Are the students confident to learn well? . (blackboard title: understanding numbers within 100 million)
Second, independent exploration, cooperation and exchanges.
Let the students know the counting unit by demonstrating the counter.
Teacher: If you want to know the number greater than 10,000, you must first know the counting unit greater than 10,000. Take out the counter and point out that the counter can help us understand the counting unit.
Teacher: I want to display 9000 on the counter. How do I dial the ball?
Health: dial nine beads and thousands. (Students introduce while doing the operation)
Teacher: Put another bead on a thousand. What is it now?
Health: 10000 10. One thousand is ten thousand.
Teacher: If I put six beads in ten thousand places, how many are there altogether? How about four more beads?
Health: one hundred thousand, 10. Ten thousand is one hundred thousand.
Teacher: How much is100000? 10. Where's 1 million?
Health: 65438+100000 is1000000. 10 1 million is 10 million.
Teacher: Can you use the counter 1. 1 100 million?
It means that one student counts pearls while drawing them, and other students count them with him while watching them: 1 0 million, 20 million, 30 million ... 90 million, 1 100 million,1100 million. Some students counted down to 100 million, but immediately realized that it was wrong. It should be 1 billion. Tens of millions of students have played 10 pearls, and hundreds of millions have played a pearl, which means that 1 010 million is1billion.
Teacher: The 10,000, 100,000, 1 million, 10 million and 100 million we just knew are all counting units. What units of counting have we learned before?
Health: One, ten, one hundred, one thousand. (The teacher writes the students' answers on the blackboard)
Teacher: The positions represented by these counting units are called numbers. What do these counting units represent?
Student: Unit, ten, hundred, thousand, ten thousand, one hundred thousand, one million, ten million, one hundred million ... (Teacher and students answer the blackboard together)
Teacher: According to our country's counting habit, every four digits from the right are one level. Units, 10, 100 and 1000 are levels, indicating how many "units" there are; Ten thousand digits, one hundred thousand digits, one million digits and ten million digits are all ten thousand digits, which means how many "tens of thousands".
The courseware shows the population of Baoding with a numerical sequence table.
Teacher: This is the latest population data of Baoding after the sixth census. Let's see where the number 9 is. What does this mean?
Health: 9 is in Wan Li, which means more than 90 thousand.
Teacher: Can you tell me what the numbers on other numbers mean, like this classmate just now? Two people at the same table said to each other.
After speaking at the same table, the group revised it.
Teacher: Did you find anything during the conversation?
Health: Three 1 have different meanings, that is to say, if the same number is written in different digits, it represents different counting units.
Teacher: With what we have just learned, we can read some large numbers within 100 million (Example 2 in the courseware). Can you try to read it yourself first? (After giving students 1 minute to think or read silently) Read aloud to each other in the group first, and compare who reads best.
Teacher: Which group would like to read these numbers to you?
Each member of the group reads a number, and other students use gestures to judge whether they read it correctly.
Teacher: Please look at the difference between this number and the previous number (5462 1) (students may say it is not an integer). Who can read this number (let students try to read it)?
Teacher: Everyone can read these numbers, so how to read other large numbers? Should we summarize the reading methods and try to summarize them in combination with these problems: (courseware demonstration)
1, how to pronounce two series?
2. What's the difference between ten thousand series and one order number?
3. How to read zero in a number?
Requirements: think independently first, and then communicate in groups.
After the students exchanged ideas, the group representatives spoke:
Health 1: there are two levels of numbers, first read 10,000 levels, and then read another level;
Student 2: the pronunciation of the ten thousand series is the same as that of the first level, but the word "ten thousand" should be added after reading;
Health 3: Don't read the zero at the end. For example, if the four zeros of 24960000 are at the end, don't read it. 0 on the scale of 64,070,000 million is at the end. If you don't read it, use "ten" instead. The three zeros after 7 are also the last ones not to be read. Consider it 7000. No matter whether there is one or several zeros in the middle, only one "zero" is read. The content of the teacher's courseware while the students report.
Teacher: This group of students summed up completely and accurately. Look at the big screen and write down the pronunciation of numbers within 100 million. (Free reading for students 1 min)
Third, consolidate new knowledge:
1, counting as required.
2. Fill in the numerical sequence table.
3. reading.
Teacher: Let's read some numbers by reading! The courseware shows the pictures and data at the beginning of the class, and students write their reading methods in their exercise books independently.
After the students finish writing, the whole class corrects it.
Teacher: Large numbers exist widely in our lives. You can always find them as long as you pay attention. How time flies! This class is coming to an end. The teacher left an assignment for everyone after class: collect large numbers in life, record them and read them out.
Fourth, the class summary:
What did you learn from this course? Let's talk about it together (Talk to 2-3 classmates and sit at the same table)