Knowledge point arrangement in the second volume of the third grade

Decimal part:

1, meaning of score: divide the unit "1" into several parts on average, and the number representing one or several parts is called a score. The number representing one of them is called a fractional unit.

For example, 23 is to divide a whole into three parts and take two of them.

Molecule (indicate how many copies to copy)

Fraction line (indicating average score)

Denominator (meaning to divide the whole into several parts on average)

The decimal unit of 23 is 13, and it has two such decimal units.

2. The basic nature of the fraction: the numerator and denominator of the fraction are multiplied or divided by the same number at the same time (except 0), and the size of the fraction remains unchanged.

For example,13 = 26 = 39 = 4121620 = 810 = 45.

3, the score contrast size:

(1) Compared with the denominator score, the higher the numerator, the higher the score. For example:

(2) Compared with the molecular fraction, the fraction with smaller denominator is larger. For example:

(3) Compare the scores with different numerators and denominators, and first convert the scores into those with the same mother before comparing them.

For example:

4. Fractional addition and subtraction:

(1) Fractions with the same denominator are added and subtracted, while the denominator remains the same, and the numerator is added and subtracted.

Such as: 25+35 = 55 =189-19 = 79.

(2) Addition and subtraction of fractions with different denominators are divided into fractions with the same denominator first, and then added and subtracted.

For example:

Decimal part:

1, the concept of decimal:

Numbers like 5.83, 12.5, 16.72, 0.8 are called decimals.

2. The name of the decimal part:

Reading: 56.83

3. Decimal comparison size:

Decimal comparison size, first compare the integer part, the larger the integer part; If the integer parts are the same, compare the first place of the decimal part; If the first digit of the decimal part is the same, compare the second digit of the decimal part. ...

For example:

4, decimal addition and subtraction:

When adding and subtracting two decimal places vertically, the decimal points should be aligned.

For example:

Direction and position

1. In real life, we judge that the direction is to get up in the morning and face the sun, with the east in front, the west behind, the north on the left and the south on the right.

2. South and North are opposite, and East and West are opposite.

3. Maps are generally drawn from four directions: north, south, left and right.

Translation and rotation

1. Translation: Both the elevator and the cable car move in a certain direction as a whole, which is called translation.

Such as: raising the national flag; Pull the drawer; The movement of the elevator; Cable car, etc.

2. Rotation: When the windmill and fan rotate, the position is fixed and always rotates around a fixed point. This phenomenon is called rotation.

Such as: the rotation of the ferris wheel; The rotation of the hour hand, minute hand and second hand on the clock face; Screw the bottle cap, etc.

3. Axisymmetric figure: A figure with two sides folded in half and completely overlapped is called an axisymmetric figure.

The straight line where the crease lies is called the symmetry axis.

Such as rectangle, square, circle, etc.

Two digits multiplied by two or three digits.

1, it is easier to find the sum of several identical addends by multiplication. (What is a few, multiply)

What is the sum of eight 50+? 50×8=400

What is 10 90? 90× 10=900

2. Find out how many times a number is and calculate it by multiplication.

What is 20 times of 14? 14×20=280

Area of rectangle and square

1, the surface size of an object or a closed figure is called their area.

2. The related formula of square:

The circumference of a square = side length × 4; Side length = perimeter ÷ 4;

Area of a square = side length × side length.

3. Rectangular correlation formula:

The circumference of a rectangle = (length+width) × 2; Length = perimeter ÷2- width; Width = perimeter ÷2- length.

Area of rectangle = length × width; Length = area ÷ width; Width = area ÷ length.

4. Area unit:

(1) The propulsion rate between every two adjacent length units is 10.

1 m = 10 decimeter; 1 decimeter = 10/0cm; 1 m = 100 cm ...

Kilometers □□ meters decimeters centimeters millimeters

(2) The propulsion rate between every two adjacent regional units is 100.

1 m2 = 100 square decimeter; 1 square decimeter = 100 square centimeter; 1 m2 = 10000 cm2;

1 km2 = 100 hectare; 1 hectare =10000m2; 1 km2 = 1000000 m2 ...

Square kilometer hectare □ square meter square centimeter square millimeter

Position and direction of the first unit

L knowledge points:

(1) Know eight directions: east, south, west, north, northeast, southeast, northwest and southwest.

1. How to tell the direction: You can tell the direction with the help of things around you, such as the sun, or with the help of tools such as a compass.

2. Be able to determine the other seven directions according to one direction and know which directions are relative. South-north, west-east; Northwest-southeast, northeast-southwest.

3. Know the direction on the map: up north, down south, left west, right east. (Book: Exercise 1, questions 3 and 4; )

4. Understand the method of drawing a simple schematic diagram: first determine the observation point, draw the selected observation point in the center of the plane, and then determine the direction of each object relative to the observation point. Draw on paper according to "up north, down south, left west, right east" and mark the north with the arrow "↑". (Book: Exercise 2, Question 2. )

5. And can read the map. P4 Example 2: Know the direction of a building or place on the whole map, and the positional relationship between two places on the map: who is in whose direction, etc. Big Ben p 1 double base training.

(2) Look at the simple road map to describe the walking route.

1. Look at the simple road map: first determine your position, take your position as the center, then determine the direction of the destination and the surrounding things according to the law of going up north, down south, left west, right east, and finally determine the route to take according to the direction and distance of the destination.

2. Method of describing the walking route: Based on the starting point, see which road leads to the destination, and finally describe the walking route (where to go first, then where to go). Sometimes you have to explain how far it is. (Book: p5 Do it; P9 did it; (Big Ben: 1 and 2 questions on the left of p3; Question 65438+ right 0, 2, 3; )

3. Comprehensive topic: give a road map, tell the way out of a place, and calculate the time, speed, or arrival time, how much the ticket is, etc. According to the information. (Big Ben: the P5 problem 1 and 3. )

The divisor of the second unit is the division of a number.

L knowledge points:

Oral grouping

1. The oral calculation method of dividing thousands, hundreds and tens by one digit (P 14 cases 1)

(1) divisor calculation in the table: divide the number before the dividend 0 by one bit. After calculating the result, look at how many zeros there are at the end of the dividend, and then add a few zeros after the calculated result.

(2) Multiply first and calculate division: See how many times a number is equal to the dividend, and the multiplied number is the quotient.

2. Estimation method of dividing three digits by one digit (P 16, second case):

The divisor of (1) is constant, and the three digits are regarded as hundred, ten or even hundred, and then calculated by the basic method of oral calculation.

(2) Thinking formula estimation: Think about how many times a number is closest to or equal to the highest digit or the first two digits of the dividend, and hundreds or dozens is the quotient to be estimated.

(b) Written division of labour

1. Firmly grasp the writing methods, steps and formats of dividing two digits by one digit and dividing three digits by one digit, especially the writing methods of writing formulas ending in 0 in the middle of quotient. (p29 cases 6; P3 1 case 7)

2. Will judge how many digits the quotient is. (p24 question 5)

3. Know the calculation method of division:

(1) Division without residue: quotient× divisor = dividend;

(2) Division with remainder: quotient × divisor+remainder = dividend;

4. Remember some rules about 0:

(1)0 is not divisible.

(2) The divisor of the same two numbers is 1. Since this number is divisible, it is not 0. )

(3) Divide 0 by any number that is not 0 to get 0.

(3) Special reminder:

1. Pay special attention to oral calculation, estimation and written calculation, where there are zeros in the middle and at the end.

2. See clearly the requirements of the application problem and choose the appropriate method to solve the problem. Oral calculation questions can be calculated directly in the form of columns; Pay attention to the writing format of the estimation question:124 ÷ 3 ≈ 40; It's best to write vertical scores in the calculation questions. (Book p35, Question 1, 2, 3)

Unit 3 Statistics

L knowledge points:

1. I can read bar charts and bar charts where the starting cell is different from the unit represented by other cells. Can complete the statistical chart according to the data in the statistical table, and the data must be marked on the completed statistical chart.

2. Be able to analyze according to statistical charts and solve simple practical problems (application problems). Be able to ask simple questions and answer them according to statistical charts and tables. For example, book P45, question 2.

3. Be able to make simple data analysis and put forward reasonable suggestions according to the contents in statistical charts. For example, the book P39.

4. Understand the meaning of average, and give a set of data to find their average. For example, the height of three girls: 135 cm, 140 cm, 132 cm. Find the average height. Remember the format of the average. Divide the total number by the total number of shares: (++……+) ÷ Calculate p42 in parallel. Will check whether the average is right or wrong. The average value must be between the maximum and minimum values.

5. The average value will be used to compare the overall situation of the two groups of data. Question 4 on page 45 of the book. What kind of cookies do you want? The average monthly sales volume in the first quarter is much, how much more. Analyze the reasons for the increase in sales of the second type of biscuits.

6. Give the average and several data, and then find another data. For example, Xiaoming scored an average of 85 in three subjects, including 83 in foreign languages and 80 in mathematics. What's the score for Chinese?

7. Comprehensive topics combining knowledge points such as time and speed.

Please refer to the statistics in the textbook.

Unit 4 "Year Month Day"

L knowledge points:

(a) Year, month and day.

1. Memorize the number of days in each month, knowing that there are 3 1 day in the big month and 30 days in the small month. February 28th in a normal year, February 29th in a leap year, and February is neither a big moon nor a small moon. There are 12 months, 7 big months and 4 small months in a year.

You can remember them by folk songs: January, Wednesday, Friday, July, August, October and December.

3 1 day is never bad,

Four, six, nine and thirty in winter (winter is November)

February 28th in a normal year and February 29th in a leap year.

2. Remember the number of days in a year: 365 days in a normal year and 366 days in a leap year. How many days in the first half of the year (average year 18 1 day, leap year 182 days) and how many days in the second half of the year (184 days).

3. We know that 1 is the first quarter in February, the second quarter in April, May and June, the third quarter in July, August and September, and the fourth quarter in 1 1, 12. How many days are there in each quarter and how many days are there in consecutive months will be calculated. Two consecutive months ***62 days are: July and August, 65438+ February of the following year and 65438+ 10; There are 62 days in two consecutive months in a year: July and August.

4. Given the number of days, calculate how many weeks and how many days. For example, the third quarter has (92) days and (13) weeks and zero (1) days. A normal year has (365) days, that is, (52) week zero (1) days.

5. Gregorian calendar years that are multiples of 4 are generally leap years; Generally speaking, a leap year in a normal year can be judged by dividing the year by 4. When a year is divided by 4, the remainder is a flat year, and no remainder is a leap year. For example, 1978 ÷ 4 = 494...2, 1978 is a normal year.

1988÷4=497, 1988 is a leap year.

6. If the Gregorian calendar year is 100, it must be a multiple of 400 to be considered as a leap year. For example, 1900 is a normal year and 2000 is a leap year. See page 49.

7. Given a person's year of birth, what is his age? Knowing a person's age, you can figure out what year he was born. For example, Xiaohua 1994 was born in June this year (15 years old). Xiaohua 12 years old. He was born in (1997).

8. Remember that the founding date is19491kloc-0/,and you can calculate the anniversary of the founding of this year (or any year). For example, 1999 is the 50th anniversary of the founding of People's Republic of China (PRC); This year marks the 60th anniversary of the founding of People's Republic of China (PRC).

(2) 24-hour timing method

1. The 24-hour clock method will be used to indicate the time; The ordinary timing method and the 24-hour timing method will be interchanged.

Such as: ordinary timing method, 24-hour timing method.

9 a.m

9 p.m. 265438+ 0 p.m.

Common timing methods must be prefixed with "morning" and "afternoon".

2. Run time, start time and end time will be calculated. Know the difference between time and moment. For example, the train 1 1: 00, 2 1: 30 arrives, and the train running time is (10: 30). Be careful not to write (10: 30).

The correct column format is: 21:30-11:10: 30. Subtraction cannot be done in the form of a spreadsheet.

Another example: the train 19 leaves and arrives at 8 o'clock the next day. Train running time is (13 hours). For those who span two days, you can first calculate how long it took on the first day: 24- 19 = 5 (hours), plus 8 hours of driving the next day: 5+8= 13 (hours).

For another example, a ball game started at 19: 30 and lasted for 155 minutes. What time does the game end? Convert first, 155 = 2: 35, and then calculate.

3. Make a monthly calendar and an annual calendar according to the given information. For example, if a certain year 1 is Tuesday, then make an August calendar. Another example: April 30th of a certain year is Thursday, and I made a monthly calendar in May.