1.
Concept of square: A quadrilateral with four equal sides and four right angles is a square.
Features: There are four right angles and four sides are equal. A square is both a rectangle and a diamond.
Perimeter: the circumference of a square = side length ×4.
rectangle
Concept: A parallelogram with a right angle is called a rectangle.
Features: A rectangle has two lengths, two widths, four right angles and equal opposite sides.
Perimeter: the circumference of a rectangle = (length+width) ×2.
parallelogram
Concept: Two groups of quadrangles with parallel opposite sides, with parallel opposite sides and equal diagonals. (Square and rectangle belong to special parallelogram)
Features:
(1) The opposite sides are equal and the diagonal lines are equal.
② Parallelogram is easy to deform.
Perimeter: perimeter of parallelogram = side length of two sides plus ×2.
trapeziform
Concept: A quadrilateral with one set of parallel opposite sides and another set of non-parallel opposite sides.
Features: Only one set of opposite sides is parallel.
Circumference: upper sole+lower sole+waist circumference
isosceles trapezoid
Concept: Two isosceles trapezoids with equal bottom angles are axisymmetric figures with symmetry axes.
Features: there are a group of parallel opposite sides, with equal waist length.
Circumference: upper sole+lower sole+waist circumference
diamond
Concept: A set of parallel four-sided rows with equal adjacent sides is a diamond.
Features:
All four sides are equal.
(2) diagonal vertical bisection.
③ A diagonal line bisects a set of diagonal lines respectively.
Perimeter: two different side lengths plus ×2.
What is the connection between each quadrilateral?
1, a square is both a rectangle and a diamond.
2. Square and rectangle belong to special parallelogram.
3. Square or special rectangle.
2. Sorting out the knowledge points of mathematics in the third grade of primary school
A preliminary understanding of the fraction 1, the meaning of the fraction: divide a whole into several parts, which means that several parts are parts of the whole, the divided part is the denominator, and the taken part is the numerator.
2. Fraction: divide an object or a figure into several parts on average, and each part is a fraction of it. Score: divide an object or figure into several parts, and take a few parts, which is the score of the object or figure.
3. The more shares a whole is divided equally, the smaller the number each share represents.
4. The method of comparing scores.
The numerator of (1) is the same, but the fraction with small denominator is large, and the fraction with large denominator is small.
(2) The denominator is the same, the numerator is large, and the numerator is small.
5. Fractional addition and subtraction
① Calculation method of addition and subtraction of the same denominator fraction: addition and subtraction of the same denominator fraction and addition and subtraction of the same numerator fraction.
(2) Calculation method of how many fractions are subtracted from 1: When calculating how many fractions are subtracted from 1, write1as the denominator of the subtraction before calculation.
6. How to calculate that one number is a fraction of another number: first divide this number by the denominator (find out the number of copies of 1), and then use the quotient multiplier (find out what they are).
3. Sorting out the knowledge points of mathematics in the third grade of primary school
1, pay attention when calculating orally: (1)0 divided by any number (except 0) equals 0;
(2) Multiply 0 by any number to get 0;
(3)0 plus any number will get any number itself;
(4) Minus 0 from any number to get any number itself.
2. Division without residue:
Dividend = quotient
Quotient × Divider = Divider
Dividend = divisor
Division with remainder:
Dividend = quotient ... remainder
Quotient × Divider+Remainder = Divider
(Dividend-Remainder) ÷ Quotient = Divider
3. Stroke division sequence: determine the number of digits of quotient, try quotient, check, check.
(1) The written calculation method of dividing one digit by two digits (quotient is two digits): first divide the number on the tenth digit by one digit, if there is a remainder, merge the remainder with the number on the first digit, and then divide by the divisor. Write the quotient except the dividend on the dividend.
(2) The pen calculation method of dividing one digit by three digits: first divide by the digits of the dividend. If the number is not quotient 1, check the first two digits. If the number of digits of the dividend is divided, write the quotient on that number. If it is not the quotient 1, it is the quotient 0 of this digit; The remainder of each division is less than the divisor, so the number on the divisor falls, the remainder is merged, and then the division is continued.
(3) Calculation method of division:
The checking calculation method of division without residue: quotient × divisor: dividend;
Calculation method of division with remainder: quotient × divisor+remainder = dividend.
4. Basic Law:
(1) Write the quotient in that position except the high position;
(2) When three digits are divided by one digit, the quotient is three digits. If the percentile is not enough, the quotient is two digits; (If there are not enough points, just look at two businessmen. )
(3) Which bit has a remainder, it is merged with the number on the next bit and then divided;
(4) If the quotient of 1 is not enough, add 0 to occupy a place; The remainder of each division must be less than the divisor.
4. Sorting out the knowledge points of mathematics in the third grade of primary school
Addition and subtraction within ten thousand 1, reading and writing numbers (write Chinese characters when reading, and Arabic numerals when writing numbers)
No matter whether there is a zero or several zeros at the end of a number, this zero will not be read.
② There is a zero or two consecutive zeros in the middle of a number, and both of them read only one zero.
2. Comparison of figures:
① Numbers with different digits are larger, and those with more digits are larger.
(2) Compare the sizes of numbers with the same number of digits. First, compare the numbers on the numbers of these two numbers. If two digits are the same, compare the next digit, and so on.
4. Find the approximate value of a number: Look at the last digit. If it is 0-4, use the four-shed method. If it's 5-9, use the decimal method.
5, the minuend is a three-digit continuous abdication subtraction steps:
① When the columns are vertical, the same numbers must be aligned;
(2) When subtracting, which digit is not reduced enough, subtract 1 from the last digit and add10 to the standard; If the previous digit is 0, it is 1 of the previous digit.
5. Sorting out the knowledge points of mathematics in the third grade of primary school
Measure 1. In daily life, a small number of items can be used as units (millimeters, centimeters, decimeters); Large objects are usually measured in meters; Generally, the unit for measuring long distances is (km), also called (km).
2. 1 The thickness of coins, rulers, magnetic cards, buttons and keys 1 min is about1mm..
3. When calculating the length, you can only add or subtract the same length unit.
4. The relationship between length units is as follows: (the propulsion rate between every two adjacent length units is 10).
① the advancing rate is 10: 1 m = 10 decimeter, 1 decimeter = 10 cm, 10 mm,10 mm.
② The advancing speed is 1 00:1m =100 cm,1decimeter = 100 mm, 100 cm = 1 m,/kloc-0.
③ The forward speed is1000:1km =1000 m,1km = 1000m = 1km.
When we express the weight of an object, we usually use (mass unit). In life, the weight of lighter items can be measured in grams. According to the quality of general goods, it is usually a unit (kg); Measure the mass of heavy or bulk goods, usually in tons.
6. The ratio of two adjacent mass units is 1000.
1 ton = 1 000kg/kg = 1 000g1000kg = 1 ton1000g =1kg.