Knowledge points of "knowing numbers within 10,000" in the second grade mathematics of the first primary school
First, the understanding of numbers within 1000, 1, 10, one hundred is one thousand.
2. When reading, read from a height. There are hundreds in a hundred, ten in ten, and a zero in the middle. No matter how many zeros there are in the end, you don't read them.
3. When writing numbers, you should start from the high position, with hundreds of digits, ten digits and ten digits. Any number without a number will be written as zero.
4. Composition of numbers: According to what number is on each number, it consists of several such counting units.
Second, the understanding of the number within 10000
1, 10 One thousand is ten thousand.
2. Numbers within 10,000 are the same as those within 1000.
3. The minimum two digits are 10, and the two digits of are 99; The minimum three digits are 100, and the three digits are 999; The smallest four digits are 1000, and the four digits are 9999; The smallest five digits are 10000, and the five digits of are 99999.
Three, the whole hundred, integer thousand addition and subtraction
Addition and subtraction methods of 1, integer hundred and integer thousand.
(1) Look at the whole hundred and the whole thousand, and then add and subtract.
(2) Add and subtract the number before 0, and then add the same number of zeros as integer hundred and integer thousand at the end of the obtained number.
Step 2 estimate
Teaching plan of "knowing numbers within 10,000" in the second grade of second primary school.
Design Description: The recognition of numbers within ten thousand is the third stage of digital recognition, but its basic principle is always decimal counting. Due to the age characteristics of junior two students, their ability to understand abstract concepts has not yet formed. Therefore, on the basis of students' understanding of the four digits of "one, ten, hundred and thousand", let students fully experience the counting process and the formation process of numbers from concrete form to abstract form, understand and master the knowledge point of "10 thousand is 10000", and deepen their understanding of decimal counting methods.
1, the combination of numbers and shapes, step by step, deepen understanding.
The teaching of this lesson begins with the situation diagram, which makes students feel the application of numbers in their lives, and then makes students use cubes as materials to make 11 thousand places; Then take the counter as the material and count eleven thousand digits, so that students can further understand the decimal counting principle and understand that "10 thousand is ten thousand". Finally, guiding students to make a digital sequence table can stimulate students' interest in learning, make them further understand the meaning and function of numbers, and explore the application value of digital sequence tables.
2. From intuition to abstraction, deepen the understanding of concepts.
The teaching of this lesson focuses on letting students experience the process of counting, allowing students to count fully through the activity of counting stars, and deepening students' understanding of counting units and counting methods in the activity. Then through the gradual abstraction of cube blocks and counters, students can intuitively feel the formation process of concepts and gradually cultivate and develop their sense of numbers.
Preparation before class:
Teachers prepare the digital sequence table of PPT courseware counters
Student preparation counter
Teaching process:
Introduce situations to stimulate interest
1, show the courseware and experience "large numbers".
(1) Introduction: Students, there is mathematics knowledge everywhere in life. Look, this is our campus. Please read these figures on campus.
(2) Students try to read.
(3) Guide students to watch the map of Nanjing Yangtze River Bridge and read: Nanjing Yangtze River Bridge is 4589 meters long and railway bridge is 6772 meters long.
2. Reveal the topic.
Teacher: In our life, it seems that there are many numbers bigger than thousands. Today, we will know them. (Title on the blackboard: Understanding Numbers within 10,000)
Design intention: By creating situations, students are guided to pay attention to the mathematical phenomena in life, and the need to know numbers within 10,000 is generated, and the relationship between mathematics and life is understood, so as to cultivate students' patriotic feelings.
Explore new knowledge and guide discovery.
(1) Teaching Example 5.
1, review the counting method.
(1) Divide the students into groups and say: What counting units have you learned? What is the forward speed between two adjacent counting units?
(2) Students collectively report the counting methods they have learned.
2. Guide the students to count the blocks of the cube.
(1) Guide students to observe the cubes in Example 5 first, and then count them.
(2) The method for students to exchange numbers collectively.
(first count 100 in ten places, then count100 in100 places, which is exactly a big cube, then 1000 places,10/kloc-0.
(3) Teacher-student perception: eleven thousand, 10 thousand is ten thousand. "Ten thousand" is also a counting unit. (blackboard writing)
Dial from one thousand to ten thousand at the counter.
(1) Please indicate the number on the counter.
(2) Students group one, thinking: When you dial 9000, what is the extra 1000? How to dial the beads?
(3) The teacher dials the beads on the counter, and at the same time guides the students to dial the number of edges, so that the students can make it clear that nine thousand Canadian dollars 1 thousand is ten thousand. We've dialed 9,000, and we need to dial another 1,000, so we have to remove nine and move forward by one to 1.
(4) Summary: Add "ten thousand" before the counting unit "thousand", and ten thousand is a larger counting unit.
4. Sort out the digital sequence table.
(1) Guide students to recall the numbers they have learned.
(Unit, ten, hundred, thousand, ten thousand)
(2) Think about the order of these numbers with the help of the counter.
(From right to left, it is unit, ten, hundred, thousand and ten thousand)
(3) Organize students to make a numerical sequence table, and the teacher will patrol for guidance.
(4) Show the number sequence table made by students and talk about the matters that should be paid attention to when making the number sequence table.
(Note that the numerical sequence table should be arranged from right to left and from low to high. )
(5) Instruct students to represent 568 and 302 on the number sequence table and read them out.
Reflections on the Teaching of Mathematics "Understanding Numbers within 10,000" in Grade Three and Grade Two of Primary School
For junior two students, "understanding numbers within 10,000" is not ignorance. They have accumulated a lot of knowledge of numbers within 10,000 on the basis of previous studies or in their lives, and some of them can even read numbers within 10,000, but they have not yet formed a systematic cognition. Through the study of this lesson, they have summarized and gradually formed a systematic knowledge system. In order to better help students organize and summarize new knowledge on the basis of the original knowledge, and effectively highlight the key points, I have broken down the course from three aspects:
First, contact with life and perceive large numbers.
Under the guidance of the new curriculum concept, mathematics strengthens life, enables students to learn valuable mathematics, mathematicizes living materials, makes mathematics teaching live, and enables students to feel the connection between mathematics and real life. Therefore, in this class, I first mathematize my life. Through pre-class investigation and classroom communication, students can find large numbers in life. I feel that there are so many large numbers in life, which leads to the necessity of learning large numbers in life and learning mathematics. Then let the students explore and abstract the large numbers in life into mathematical knowledge.
Second, use your head to think and understand the decimal relationship.
Before learning the understanding of the number within 10,000, let students know the counting unit "thousand" by counting, and count the number of big cubes by counting big cubes, so that mathematics knowledge can return to life, and students can experience the practical significance of learning mathematics in communication and further feel the necessity of learning mathematics. Among them, when counting large cubes, the method of guiding students to count is particularly important. Among them, students think that 10 is 1, 10 is 100, and 10 is 1000, from which a large number is obtained: one thousand. And use courseware to demonstrate the process of one by one, one by one, one by one, to deepen the understanding of "thousand" and understand the decimal relationship between counting units. Pave the way for understanding numbers within 10 thousand.
Third, in the form of activities, stimulate students' sense of numbers.
Students go through the process of counting in counting activities, and then know the numbers within the counting unit of "ten thousand" and 10000, and can describe things in life with specific numbers. If the traditional teaching method is used, simply giving students "10 is a thousand, and 10 is a thousand" is too blunt and preaching, and it is difficult for students to grasp the relationship between one, ten, hundred, thousand and ten thousand. Therefore, arrange activities in this class to promote the development of students' sense of numbers and enrich their understanding of numbers. First of all, before class, let students investigate and find out the large numbers in life and classroom communication. In this process, students have a preliminary understanding and feeling of large numbers. Then, arrange "guess?" Stimulate students' interest, lead to "a small cube is a part of a big cube", give students a standard estimate, and then estimate "how many small cubes are there in a big cube?" Let the students think in the estimation. It is difficult for students to understand "Wan". How to break through this difficulty and let students establish their understanding of "Wan"? Students know that "one hundred is a thousand" and "a big cube has 1000 small cubes." Then I observed the 1 book on 100 page, and then put the 10 book on 100 page together to let students feel how many books there are on 1000 page. So how many small cubes are there when 10 big cubes add up? "Let students establish a preliminary understanding of' ten thousand is ten thousand', but what is' ten thousand'? Students are still vague. I will help students understand the meaning of large numbers and feel the close relationship between mathematics and life through the experience of "guessing the number of students in school". There are about 50 students in each class in our second grade, 10 class, and there are about 500 students in the whole grade. There are six grades in the school, with 500 students in each grade. There are about 3,000 students in the school, and 3,000 is short of 7,000 and 10,000 is short. The students' union thinks that there are already many students in the school, but the number of students in the school is 3000, which is far from 10000, indicating that the number of 10000 is very large.