Mathematics knowledge points in the first volume of the fourth grade
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.
Knowledge points of mathematics triangle in the fourth grade of primary school
1, and the figure surrounded by three line segments (the endpoints of every two adjacent line segments are connected) is called a triangle.
Draw a vertical line from the vertex of the triangle to its opposite side. The line segment from the vertex to the vertical foot is called the height of the triangle, and this side is called the bottom of the triangle. This triangle is only three stories high.
3. The triangle is very stable.
4. The sum of any two sides of a triangle is greater than the third side.
A triangle with three acute angles is called an acute triangle.
6. A triangle with a right angle is called a right triangle.
7. A triangle with an obtuse angle is called an obtuse triangle.
8. Each triangle has at least two acute angles; Each triangle has at most 1 right angles; Each triangle has at most 1 obtuse angles.
9. A triangle with two equal sides is called an isosceles triangle.
10, a triangle with three equilateral sides is called an equilateral triangle, also called a regular triangle.
An equilateral triangle is a special isosceles triangle.
12, and the sum of the interior angles of the triangle is 180.
13, and the sum of the internal angles of the quadrilateral is 360.
14. Two identical triangles can be used to form a parallelogram.
15. Two identical right triangles can be combined into a parallelogram, a rectangle and a big triangle.
16. Two identical isosceles right triangles can be combined into a parallelogram and a square. Large isosceles right triangle.
Mathematics learning methods and skills
1, grab the classroom. Mathematics study focuses on weekdays and is not suitable for surprise review. The most important thing to study on weekdays is to attend class for 40 minutes. Listen attentively and keep your thoughts close to the teacher. At the same time, it should be pointed out that many students tend to ignore the mathematical ideas and methods taught by teachers and pay attention to the answers to questions. In fact, the way of thinking is far more important than the answers to some questions.
2. Complete the homework with high quality. The so-called high quality refers to high precision and high speed. When writing homework, sometimes the same type of questions will be repeated. At this time, we should consciously examine the speed and accuracy, and we can have a deeper thinking about this kind of problem every time we finish it, such as the content it examines, the mathematical thinking method used, the rules and skills of solving problems, etc. In addition, the thinking questions assigned by the teacher should also be carefully completed. If you don't give up easily, you must carry forward the spirit of "nails" and think quietly whenever you have time. Inspiration always pops up in front of you. Most importantly, this is an opportunity to challenge yourself. Success will bring self-confidence, which is very important for learning mathematics; Even if you fail, this question will leave a deep impression on you.
3. Think hard and ask more questions. First of all, for the concepts and laws given by teachers, we should not only know "why", but also know "why" and get to the bottom of it. This is the way to understand. Secondly, we should be skeptical about learning any subject, especially mathematics. If you have any questions about the teacher's explanation and the content of the textbook, please feel free to ask questions and discuss with the teacher. In a word, thinking and asking questions are the ways to eliminate hidden dangers in learning.
4. Summarize and compare, and clear your mind.
(1) summary and comparison of knowledge points. After learning a unit, you should sort out the contents of this chapter or go through it in your mind to clarify the relationship between them. Similar and confusing knowledge points should be classified and compared, and sometimes they can be distinguished by association.
(2) Summary and comparison of topics. Students can set up their own question bank. I have two sets of problem sets. One is wrong and the other is accurate. Write down the mistakes in the usual homework and exams selectively, and mark the matters needing attention with a red pen on one side. Just read what is written in red pen before the exam. I also wrote down some extremely clever or difficult problems I saw, and marked the methods and ideas used in this problem with a red pen. After a long time, I can sum up some types of problem-solving rules and write them down in red notes. In the end, they will become your precious wealth and be of great help to your math study.
5. Do extracurricular exercises seriously. Spare time is very precious to our primary school students, so you should be accurate and precise when you do extracurricular exercises. As long as you do three or two pages carefully every day, your math study will be "a tower of sand" and fruitful.
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★ 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.
★ The induction of mathematics knowledge points in the first volume of the fourth grade of primary school
★ Basic knowledge points of mathematics in the fourth grade of primary school
★ The first volume of the fourth grade math unit arranges mind maps.
★ Summarize the knowledge points of the fourth grade mathematical triangle.
★ The arrangement of mathematics knowledge points in the fourth grade of primary school
★ Basic knowledge points of mathematics in the first volume of the fourth grade
★ Key points of final review of the first volume of fourth grade mathematics
★ Summary of Mathematics Knowledge Points in Grade Four