Mathematics knowledge in the fourth grade of primary school
Translation and parallelism
Knowledge points:
1. Feel the positional relationship before and after translation-parallel. (In the same plane, two lines that never intersect are called parallel lines. )
2. Draw parallel lines.
(1) Fix the triangular ruler and draw a straight line along the right angle.
(2) Hold the ruler against the other right-angled edge of the triangular ruler, fix the ruler, and then translate the triangular ruler.
(3) Draw a straight line along the right angle.
3. You can find the parallel lines in the picture with the help of objects, plane figures or three-dimensional figures.
Supplementary knowledge points: use mathematical symbols to represent the parallel relationship between two straight lines. Such as AB∑CD.
The first volume of the fourth grade mathematics knowledge point "divisor is the division of two digits"
Oral grouping
1, divisible by ten or hundreds of dozens of oral arithmetic methods.
(1) Calculate division and want to multiply; For example, 60÷30= () can be considered as (2)×30=60.
(2) Calculated by division in the table. Use the nature of division operation: expand or shrink the dividend and divisor by the same multiple at the same time, and the quotient remains unchanged. For example, if 200÷50 wants 20÷5=4, then 200÷50=4.
2. Estimation method of dividing two digits by two digits or three digits: Division estimation is generally to "round" the numbers in the formula that are not integer ten or hundred into integer ten or hundred, and then perform oral calculation. Note that the results are marked with √.
(b) Written division of labour
1, divisor is a two-digit pen division calculation method: divide the first two digits of the dividend by the divisor first, and if the first two digits are less than the divisor, look at the first three digits. Except for the dividend, the merchants wrote it on that. The remainder after each division operation must be less than the divisor.
2. Trial-and-error method of two-digit division in which the divisor is not an integer ten: If the divisor is a two-digit number close to the integer ten, the divisor can be regarded as the trial quotient close to its integer ten by rounding, or the divisor can be regarded as the number fifteen close to it, and then the quotient can be directly determined by multiplying one digit.
3. Quotient one digit:
(1) Two digits divided by an integer, such as 62 ÷ 30;
(2) Divide three digits by an integer, such as 364÷70.
(3) Divide two digits by two digits, such as 90÷29 (try to take the quotient of 29 as 30).
(4) Divide three digits by two digits, such as: 324÷8 1 (take 8 1 as 80, and measure the quotient).
(5) Divide three digits by two digits, such as 104÷26 (take 26 as the quotient of 25).
(6) The undivided quotient of the same head is 8.9, for example, 404÷42 (the digits of the dividend are the same as the digits of the divisor, that is, "the same head", and the first two digits of the dividend are undivided, that is, "undivided", which is either quotient 8 or quotient 9. )
(7) The divider is half quotient four or five, such as: 252÷48 (24, the divisor is half of 48, which is very close to the first two digits of dividend 25, and it is either quotient 4 or quotient 5. )
4. Quotient two digits: (three digits divided by two digits)
The first two digits of (1) have a remainder, such as: 576÷ 18.
(2) The first two digits have no remainder, such as 930÷3 1.
5, the method of judging the number of digits of quotient:
Dividing the first two digits of the dividend by the divisor is not enough, and the quotient is one digit; Divide the first two digits of the dividend by the divisor, and the quotient is two digits.
(C) the changing law of quotient
1, quotient change:
The dividend of (1) remains unchanged. If the divisor is multiplied (or divided) by several (except 0), the quotient will be divided (or multiplied) by the same number.
(2) The divisor is a constant, and the quotient of the divisor multiplied (or divided) by several numbers (except 0) is also multiplied (or divided) by the same number.
2. The quotient remains unchanged: the dividend and divisor are multiplied (or divided) by the same number (except 0) at the same time, and the quotient remains unchanged.
(4) Simple calculation: remove the same number of zeros at the same time, such as 9100 ÷ 700 = 91÷ 7 =13.
How to improve the fourth-grade pupils' interest in mathematics learning?
First, create inquiry situations to stimulate interest in learning
This theory puts forward the viewpoint of "three masters": that is, classroom teaching should focus on students' development, students' inquiry learning as the main body and teachers' creative teaching as the leading factor. Therefore, in classroom teaching, teachers should create inquiry learning situations, guide students to think from multiple angles, sides and directions, stimulate students' interest in learning, and change "I want to learn" into "I want to learn".
Second, create a competitive situation to stimulate interest in learning
Educator Comenius once said that "children's desire for knowledge and learning should be stimulated by all possible means". Since we are in a big competitive environment, it is better to set up a competitive situation in our small classroom. Teachers should introduce competition mechanism in the classroom, so as to achieve "low starting point, highlight key points, disperse difficulties, attach importance to the process, slow down and encourage more." Create opportunities for students to show themselves and express themselves, and promote all students to compete, learn and catch up. For example, in a mathematics teaching and research activity, a teacher designed such a situation according to the teaching content and the psychological characteristics of primary school students. Teach "understanding of 8". When doing classroom exercises, the teacher takes out two groups of digital cards from 0 to 8, and designates a boy and a girl to represent the men's group and the women's group respectively. Although the teacher has not announced the rules and requirements of the competition at this time, all the students have entered the situation set by the teacher and secretly cheered for their team, and all the students' interest in learning has been triggered at once.
Third, create game situations to improve learning interest.
According to the characteristics of mathematics and pupils' active, innovative, curious and competitive thinking, we set up game situations, put new knowledge into game activities, make students have a desire for new knowledge through games, make students' attention in a highly concentrated state, acquire knowledge through games, develop their abilities and improve their interest in learning. For example, in class training, organize a 60-second quiz game. The teacher prepares several groups of oral math questions, divides the class into several groups, and selects three students as representatives in each group. Then the teacher asks questions and asks each group of students to answer first. The winner is the one with more scores, or a small red flag is awarded for each correct answer, and the winner is the one with more scores. In the game, students' brains are highly excited and their spirits are highly concentrated. They learned a lot of useful knowledge unconsciously, and were influenced by the correct mathematical thinking method, which effectively improved students' interest in learning.
Fourth, create story situations to stimulate interest in learning.
The art of teaching lies not in imparting skills, but in inspiring, awakening and encouraging. We think this is the essence of teaching. We properly create story situations for students in mathematics teaching, which can not only attract students' attention, but also enable students to acquire knowledge unconsciously. For example, when I was teaching the "Comparative Application" section, I told a story to my classmates during my internship: On the Mid-Autumn Festival, the governor of Jiangxi sent a tribute to Emperor Qianlong-taro, ***3 baskets, each containing 180 taro with uniform size. Emperor Qianlong was very happy and decided to give one basket to the minister of civil and military affairs and the head of the harem, and asked to press it. Xiao Shenyang, Minister of Military Affairs, was so busy that he knelt down after class. "Your majesty, I think this basket of taro is *** 180. First give it to 90 civil and military ministers and 90 harem directors respectively, and then distribute it by himself. " Small shenyang haven't say that finish, prime minister Liu Yong got off the class and knelt down. "Long live the recitation, adults just said is wrong. There are 56 civilian military commanders in the DPRK, divided into 90 taro, each with less than two, while the harem supervisor has 34 people, divided into 90 taro, each with less than three. How can this meet the average number of emperors? " The emperor nodded his head after hearing this. "Liu is right, so how do you divide it according to your opinion?" At this point, the students are attracted by the content of the story, and then let the students tell the method for Liu Yong. This story puts mathematics knowledge in the story, thus stimulating students' interest in learning.
Summarizing related articles on the knowledge points of fourth grade mathematics;
★ Knowledge points in the first volume of fourth grade mathematics
★ Summarize the knowledge points of the first volume of mathematics in the fourth grade of primary school.
★ Knowledge points of the first volume of fourth-grade mathematics in People's Education Edition
★ Summary of knowledge points for final review of fourth grade mathematics in Jiangsu Education Edition
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★ Knowledge points in the first volume of fourth-grade mathematics of Jiangsu Education Edition
★ Summarize the knowledge points of the fourth grade mathematical triangle.
★ Basic knowledge points of mathematics in the first volume of the fourth grade
★ Guidance of mathematics learning methods in the fourth grade of primary school