The knowledge point of math "hectares and square kilometers" in the first volume of the fourth grade is 1, and the area units that have been learned are square centimeters (cm2), square decimeters (dm2), square meters (m2), hectares and square kilometers (km2).
2.( 1) A square with a side length of 1cm and an area of 1cm.
(2) A square with a side length of 1 decimeter and an area of 1 square decimeter.
(3) A square with a side length of 1m and an area of 1m2.
(4) Square with side length 100 m and area 1 hectare. 1 ha = 1 10,000 m2
The area of land can be measured in hectares.
For example, the Bird's Nest covers an area of about 1 hectare. The area surrounded by the runway 400 is about 1 hectare.
(5) A square with a side length of 1000m and an area of 1 km2.
1 km2 = 100 hectares =1100 million m2.
China has a land area of about 9.6 million square kilometers.
3. Conversion between area units:
(1) First, remember the progress between them:
1 km2 = 100 hectares =1100 million m2.
1 ha = 1 10,000 m2
1 m2 = 100 square decimeter
1 square decimeter = 100 square centimeter
1 m2 = 10000 cm2
(2) conversion method:
○ 1 To convert a high-level unit into a low-level unit, it is necessary to use multiplication to calculate, just multiply the number in front of the high-level unit by the ratio between the two units. (that is, the height, the rate of progress, the decimal point moves to the right, and you can see the rate of progress by moving a few places. )
2 To aggregate low-level units into high-level units, it is necessary to calculate by division, as long as the number in front of the low-level unit is divided by the ratio between two units. (that is, reduce the level, divide by the forward speed, move the decimal point to the left, move a few positions, and see the forward speed. )
A. To convert hectares into square meters, just write four zeros directly after the data in front of hectares.
B, to convert square meters into hectares, just remove four zeros from the data in front of the square meters.
C. To convert a square kilometer into a hectare, just write two zeros directly after the data in front of the square kilometer.
D, convert a square kilometer into a square meter, just add six zeros directly after the data in front of the square kilometer.
E, to convert a square meter into a square kilometer, just remove six zeros from the data in front of the square meter.
4, fill in the legal provisions of the area unit:
(1) Land area, province (including municipality directly under the central government) area, provincial capital city area, state (city) area, county, township area, village committee and village area, generally taking "square kilometers" as the unit.
(2) Parks, colleges (schools), stadiums (gymnasiums), etc. , generally in "hectares" as the unit.
(3) Housing (building) area, classroom area, campus greening area, etc. , are generally measured in square meters.
The knowledge point of "Understanding of Large Numbers" in the first volume of fourth grade mathematics is 1. 10. Ten thousand is one hundred thousand, 10 is one million, 10 is ten million, 10 is ten 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.
The fourth grade mathematics learning method 1, to seize 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, I sometimes repeat the same type of questions. 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 summarized and compared separately, 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.
Summary of 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 in the first volume of fourth grade mathematics
★ Summary of knowledge points in the first volume of fourth grade mathematics
★ Summary of knowledge points in the fourth grade of the first volume of mathematics
★ Review the knowledge points in the first volume of fourth grade mathematics.
★ Summary of knowledge points in the final review of the fourth grade mathematics in primary school.
★ Summarize and sort out the knowledge points of fourth grade mathematics.
★ Summarize the knowledge points of the final review of the first volume of the fourth grade mathematics.
★ Knowledge points in the first volume of fourth-grade mathematics of Jiangsu Education Edition
★ Summary of knowledge points in the first volume of fourth grade mathematics (3)
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