Unit 5: Understanding of 6- 10 and Understanding of Addition and Subtraction 1. Understanding of 6- 10: 1, number: depending on the number of objects, it can be expressed by 6- 10. When counting, counting from front to back is from small to large.
2. Number sequence in10:
(1) From beginning to end: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
(2) From back to front: 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.
3. Compare size: In the order of numbers, the number behind is always greater than the number before.
4. ordinal meaning: used to indicate the order of objects, that is, which one.
5. Composition of Numbers: A number (except 0, 1) can be composed of two smaller numbers. For example, 10 consists of 9 and 1
When remembering the composition of numbers, one group of numbers can be used to associate another group of numbers in different positions.
Addition and subtraction of 2.6- 10
Calculation method of addition and subtraction within 1 and 10: according to the composition of numbers.
2. Figure 4: According to different thinking angles of a picture, two addition formulas and two subtraction formulas can be written.
3. There is a question mark under the "braces", which requires the two parts to be merged and calculated by addition. There is a question mark on the upper side of the "brace" to find out how much is left in the total and calculate it by subtraction.
Third, increase and decrease.
1. Calculation method of continuous addition: When calculating continuous addition, it should be done from left to right, first calculate the sum of the first two numbers, and then add it to the third number.
2. Calculation method of continuous subtraction: When calculating continuous subtraction, proceed from left to right. First calculate the difference between the first two numbers, and then subtract the third number from the obtained number.
Fourth, add, subtract and mix.
Calculation method of addition and subtraction: calculation is carried out from left to right. First add (or subtract) the first two numbers, and then subtract (or add) the number from the third number.
Unit 6: Understanding the number 1 1-20
1, number: according to the number of objects, it can be represented by 1 1-20. 2. Sequence: 1 1-20 The sequence is: 1 1, 12, 13, 14, 15,/kloc.
3. Comparison size: comparison can be made according to the order of numbers, and the number at the back is always greater than the number at the front, or according to the composition of numbers.
4. Composition of the number 1 1-20: All of them are composed of 1 tens and several ones, and 20 is composed of two tens. Such as: 1 ten and five 15.
5. Number of digits: the first digit on the right is one digit, and the second digit is ten digits.
6. 1 1-20 How to read each number: read dozens of digits from high places and several digits. Pronunciation of 20, 20 is pronounced: 20.
7. Write numbers: When writing numbers, write by referring to them. If there are 1 tens, write 1 in the tenth place, and write 2 if there are two tens. If there are several ones, write a few on the single digit. If there is no unit on a digit, write 0 as a placeholder.
8. Ten plus several, ten plus several and the corresponding subtraction.
(1), 10 plus several and the corresponding subtraction calculation method: 10 plus several to get ten, ten minus several to get ten, and ten minus ten to get several.
For example,10+5 =1517-7 =10/8-10 = 8.
(2) Calculation method of addition and subtraction of more than ten digits: When calculating the addition and subtraction of more than ten digits, you can use the composition of numbers to calculate, or you can add or subtract the digits and then add the whole ten.
(3) Add and subtract the names of each part:
In the addition formula, the numbers before and after the plus sign are called addends, and the numbers after the equal sign are called sums.
In the subtraction formula, the number before the minus sign is called the minuend, the number after the minus sign is called the subtraction, and the number after the equal sign is called the difference.
9. Solve the problem
To find how many numbers are between two numbers, you can use counting method or graph method. You can also use the calculation method (subtract large numbers from 1).
Know the clock
1, know the clock face: there is a number 12 on the clock face, with an hour hand and a minute hand.
Minute hand: The slender hands on the clock face are called minute hands.
Hour hand: The short hands on the clock face are called hour hands.
2. Types of clocks and watches: There are generally two kinds of clocks and watches in daily life, one is a wall clock with the number 12, minute hand and hour hand on its face. The other is an electronic watch, which has two dots on its surface and numbers around it.
3. Know the hour: the minute hand points to 12, and the hour hand points to several hours; On the electronic watch, when the right side of ":"is "00", it means the hour time, and the left side ":"means the time.
4. How to write the hour: There are two ways to write the hour: when writing or in the form of a spreadsheet. Like 8 o'clock or 8 o'clock.
Carry addition within 20
Calculation method of 1, 9 plus several: To calculate the carry addition of 9 plus several, methods such as "point number", "next number" and "decimal method" can be adopted, among which "decimal method" is relatively simple. When calculating the addition of 9 by the method of "ten times ten", 9 is added to 10 and needs 1, and then the smaller number is divided into 1 and several, and the addition of 10 is more than ten.
2, 8, 7, 6 plus several calculation methods:
(1) points;
(2) the next number;
(3) Add ten methods at most. Can be "large number division, decimal rounding" or "decimal division, large number rounding".
3, 5, 4, 3, 2 plus several calculation methods:
(1) "Split large numbers and round decimal places".
(2) "Decimal split, large number rounded".
Step 4 solve the problem
(1) When solving a problem, we can observe and analyze it from different angles, so as to find different ways to solve the problem.
(2) The practical problem of finding the total is calculated by addition.