Basic knowledge points of mathematics in the first volume of the fourth grade
1, line
(1) straight line
A straight line has no end; Infinitely long; You can draw countless lines after one o'clock, and only one straight line after two o'clock.
(2) Ray
Ray has only one endpoint; Infinitely long.
⑶ line segment
A line segment has two endpoints, which are part of a straight line; Limited length; In the connection between two points, the segment is the shortest.
The length of the line segment between two points is the distance between two points.
Connection of straight ray line segments: all are straight lines, and both rays and line segments are part of a straight line.
(4) The positional relationship between two straight lines in the same plane is parallel and intersecting.
5] parallel lines
Two straight lines defined on the same plane and not intersecting are called parallel lines. The straight line A is parallel to B, and the straight line B is also parallel to A. ..
At a point outside the straight line, you can only draw a straight line parallel to the known straight line.
There are countless vertical segments between two parallel lines, all of which are equal in length. The vertical segments between parallel lines are equal everywhere.
The painting method is one in two, three moves and four paintings.
[6] vertical line
When two straight lines intersect at right angles, they are said to be perpendicular to each other, one of them is said to be perpendicular to the other, and the intersection point is called vertical foot.
nature
After a point (on or off the line), you can only draw a straight line perpendicular to the known straight line.
The vertical line segment drawn from a point outside the straight line is the shortest, and its length is called the distance from that point to the straight line.
The painting method is one in two, three in three and four in four.
2. Angle
The definition of (1) angle leads to two rays from a point, and the graph is called an angle. This point is called the vertex of the angle, and these two rays are called the edges of the angle.
(2) Angle measurement Angle measurement unit is "degree", with the symbol "". Divide the semicircle into 180 equal parts, and the angle of each part is 1 degree. Write "1".
(3) Comparison of the size of the angle The size of the angle has nothing to do with the length drawn on both sides of the angle. The size of the angle depends on the size of both sides. The bigger the fork, the bigger the angle.
(4) The drawing method of angle is to draw a line, measure the angle, connect three lines and mark four. The angle a pair of triangles can draw is a multiple of 15.
Knowledge points of Understanding Large Numbers, the first volume of fourth grade mathematics
1.1010,000 is 100,000,1010,000 is 1 million,101 million is 10 million,1010 million is 100 million.
The advance rate between every two adjacent counting units is "10". This counting method is called decimal counting method.
Special attention: the difference between counting units and numbers.
2. When using numbers to represent numbers, these counting units should be arranged in a certain order, and their positions are called numbers.
3. Number of digits: A number contains several digits, that is, several digits. For example, 652 100 is a six-digit number.
According to our country's counting habit, every four digits are counted from the right.
5. How to pronounce hundreds of millions or more:
(1) Grading first, starting from high reading. Read level 100 million, then level 10,000, and finally level 1.
(2) Hundreds of millions should be read according to the pronunciation of hundreds of millions, and then the word "hundreds of millions" should be added at the end. Ten thousand series should be read according to the reading method of ten thousand series, and then the word "ten thousand" should be added after it.
No matter how many zeros there are at the end of each level, don't read them. Other numbers have a "0" or several "0" in succession, all of which are read only.
6, hundreds of millions of words:
(1) Write from bits, first write 100 million levels, then write 10,000 levels, and finally write one level.
(2) If there is no unit, just write 0 on the number.
7, compare the size of the quantity:
The two numbers are different, the one with more numbers is bigger and the one with fewer numbers is smaller.
(2) Two numbers with the same number of digits, starting from the number of digits, the number with the largest number of digits is larger. If the numbers on the numbers are the same, compare the numbers on the next number until the size is compared.
8. Number of rewrites:
Rewrite it into a number in the unit of "10000" or "10000000". Draw a grading line first, divide the integer 10 thousand or integer 100 thousand into four levels, then omit four zeros from each level and replace them with the word "100 thousand"
9. Find out the approximate figures:
The mantissa after omitting ten thousand digits depends on the number on one thousand digits; The mantissa after omitting 1 100 million bits depends on the number on1100 million bits.
When calculating the divisor by "rounding", it depends on whether the number of the omitted mantissa part is less than 5 or equal to or greater than 5. If it is less than 5, the mantissa is discarded and rewritten as a corresponding number of zeros; If it is equal to or greater than 5, advance 1, then discard the mantissa and rewrite it as a corresponding number of zeros.
10, indicating the number of objects: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ... are all natural numbers. There is no object, which is represented by 0, and 0 is also a natural number. All natural numbers are integers.
1 1, the smallest natural number is 0, there is no natural number, and the number of natural numbers is infinite.
12, calculator ON/CE: switch the clear screen key to clear the contents on the display screen.
AC: Clear the key, clear everything.
DEL: Clear the wrong number or operation symbol just entered.
Math learning methods in the fourth grade
First of all, create a good start and stimulate interest.
A good beginning is half the battle. Teachers should first bring smiles into the classroom, infect students with teachers' good taste, promote students to form a good psychological situation, and make necessary psychological preparations for a class. If the prologue is well spoken, it will make students eager to pursue new knowledge, stimulate their interest in learning and attract their attention, just like throwing a stone on a calm lake, which will arouse the ripples of thinking and produce the appeal that they are eager to listen to. Therefore, we should strive to launch a new curriculum of "novelty, interest, strangeness and novelty".
Second, create problem situations and implement heuristic teaching to stimulate students' cognitive interest.
The new curriculum advocates heuristic teaching. Heuristic teaching has great advantages over traditional cramming teaching. To implement heuristic teaching, the key is to create problem situations. Creating problem situations refers to learning situations that are difficult and require students to work hard and try their best. So how to create a problem situation better? This requires teachers to study textbooks carefully, dig deep into the internal laws of knowledge and the relationship between old and new knowledge, fully understand the existing cognitive structure of students, and stimulate students' interest and positive thinking activities through ingenious forms, thus creating a good problem situation. For example, in the first class, I used the method of telling stories to create problem situations. I first drew a beautiful forest on the blackboard, and then pasted a white rabbit, a red panda, a lion, a squirrel and a pony in turn. Storytelling: A group of cute little animals came to the beautiful forest. They all moved to their new homes today. Now, let's go and see where they all live ... In this class, the teacher created a vivid and interesting question situation. We make up stories and tell stories together, which makes students feel that they have entered a beautiful home. Stimulate students' interest and induce further positive thinking activities through more ingenious and novel forms.
Third, change the presentation of examples and exercises to stimulate students' interest in learning.
The new textbook provides rich teaching resources for teachers, and the presentation of mathematics content in the textbook is also close to the reality of children's life, which conforms to the age characteristics of first-year students. But these things are still static after all, and they still lack the attention and interest of students. Children in lower grades are often more interested in active things. If we can make these static resources active and further increase their interest, we will be able to firmly grasp the students' eyes. For example, in the teaching of "10 understanding", I designed ten numbers from 0 to 90 as anthropomorphic "digital children" and presented them on the blackboard one by one. Seeing that abstract numbers have grown into hands and feet and become elves who can cry and laugh, students' enthusiasm is extremely high.
Fourth, let students operate the experience and stimulate students' interest.
(A) let students "enter" the exercises in the textbook. When I let students practice, I like to let them imagine the characters in the book as themselves. Because of this, students will feel as if this topic is closer to them and feel more intimate.
(B) to create practical opportunities for students to participate, so that they can experience success in participation. For example, in the teaching of "increasing with decreasing", I made some swan headdresses in advance, so that nine children in my class could wear them and perform the scene of swans flying around. As soon as the following children saw the "role model" of this activity, they were deeply attracted and their enthusiasm was fully mobilized. Teachers can easily highlight key points and break through difficult points.
(3) Make use of students' aggressive psychological characteristics, organize some activities such as math games and answering questions in competitions, so that every student has the opportunity to participate. Learning competition is induced by ranking or winning prizes in the competition, which can stimulate students' need for self-improvement, thus improving students' learning enthusiasm and affecting learning effect to a certain extent. Generally speaking, learning competitions affect middle-level students, so most children will make continuous progress through hard work in the competition. If competition and self-competition are combined, advanced students will be more advanced, and backward students will also become advanced. This also helps to prevent students' pride and inferiority. For example, in the revision class of addition, subtraction, multiplication and division, addition, subtraction, multiplication and division and mixed addition and subtraction within 10, I adopted the way of group competition, so that every student had the opportunity to participate. The competition is divided into three parts: oral calculation, I am a small examiner, eager to answer thinking questions. Each item is participated by the whole class, and different people are selected from each group to judge and recorded in the scores of that group. Because the students have a strong sense of collective honor, reviewing their lessons in the form of competitions has greatly improved their enthusiasm for learning, and the classroom arrangement is also hierarchical. Students' mathematical thinking ability and understanding ability have been further improved, and their language expression ability has also been greatly improved.
Jiangsu Education Publishing House arranges related articles about fourth-grade mathematics knowledge points;
★ Summary of knowledge points for final review of fourth grade mathematics in Jiangsu Education Edition
★ Knowledge points in the first volume of fourth-grade mathematics of Jiangsu Education Edition
★ Su Jiaoban Primary School Grade Four Mathematics Volume I Review Data Arrangement
★ Knowledge points of fourth-grade mathematics in Jiangsu Education Edition
★ Four-grade mathematics knowledge points Su Jiaoban
★ Summarize and sort out the knowledge points of fourth grade mathematics.
★ Organize the knowledge points of fourth grade mathematics.
★ Mathematics arrangement and review of the first volume of the fourth grade of Jiangsu Education Edition
★ Su Jiaoban fourth grade mathematics review outline
★ Jiangsu Education Publishing House, the first volume of the fourth grade mathematics, arranges and reviews the review plan.