Beijing normal university edition: knowledge points of mathematical observation objects in the third grade of primary school
Knowledge of observing objects: a square: four sides are equal, two groups of opposite sides are parallel, and four corners are right angles.
Rectangular: the opposite sides are equal, the two groups of opposite sides are parallel respectively, and the four corners are right angles.
Parallelogram: the opposite sides are equal, two groups of opposite sides are parallel, and two groups of diagonal lines are equal.
Trapezoid: Only one set of opposite sides are parallel, and the isosceles trapezoid is equal to the two angles on the bottom.
Knowledge points of observing objects II
1. Observation and summary of simple objects in life: the same object will have different shapes from different angles.
2. Summary: The same three-dimensional figure will have different shapes from different angles.
Beijing normal university edition: knowledge points of mixed operation of mathematics in grade three of primary school
Knowledge point 1 1, addition, subtraction, multiplication and division are called four operations.
2. In the formula without brackets, if there is only addition, subtraction or multiplication and division, it should be calculated from left to right.
3. There are multiplication, division and addition and subtraction in the formula without brackets, and multiplication and division must be calculated first, then addition and subtraction.
4. If there are brackets in the formula, count the inner side of brackets first, and then the outer side of brackets; The calculation order of the formulas in brackets follows the above calculation order.
Knowledge point 2
On the operation of "0"
1 and "0" are inseparable; Letter means: 0 error.
2. Add 0 to a number to get the original number; The letter means: A+0 = A.
3. Subtract 0 from a number to get the original number; The letter means: a-0 = a.
4. The minuend is equal to the minuend, and the difference is 0; Letter: a-a=0
5, a number multiplied by 0, still get 0; Letter: a×0=0
6. Divide 0 by any number other than 0 to get 0; The letter means: 0÷a(a≠0)=0.
7,0 ÷ 0 can't get the fixed quotient; 5÷0 can't get the business.
Beijing normal university edition: knowledge points of addition and subtraction mathematics in the third grade of primary school
Jia Lian 256+274+36 1=89 1
When calculating the continuous addition problem, it should be calculated from left to right.
Continuous reduction
786-284-249=253
When calculating the continuous subtraction problem, you can calculate it from left to right in turn, or you can add the two subtractions first and then subtract the sum of the two subtractions from the minuend.
786-(284+249)=253
Addition-subtraction mixing
259+ 148-342=65
The operation order of the mixed problem of addition and subtraction without brackets is calculated from left to right. The operation order of the mixed problem of addition and subtraction with brackets: first in brackets, then outside brackets.
There is something wrong with the odometer.
To find the distance between the two places, we must find the correct starting point and subtract the shorter distance from the longer distance to get the distance between the two places.
Mileage = End Quantity-Start Quantity
Beijing normal university edition: knowledge points of mathematical perimeter formula in grade three of primary school
1. Perimeter concept: the length of a closed graph is its perimeter. 2. Perimeter formula:
Perimeter of rectangle
= (length+width) ×2 Rectangular length = perimeter ÷2- wide rectangular width = perimeter ÷2- length
The circumference of a square
= side length of a square ×4 side length = perimeter ÷4
Beijing normal university edition: knowledge points of mathematical division in the third grade of primary school
Relationship between 1, remainder and divisor: When calculating division with remainder, the remainder in the result must be less than divisor. 2. Formula:
Dividend = Divider× Quotient+Remainder
Divider = (Dividend-Remainder) ÷Quotient
Quotient = (dividend-remainder) divider
3. Methods:
(1) The same number is aligned, and the quotient is written on the number from digital division to digital division. If the number of digits of the dividend is less than the divisor, it depends on the first two digits of the dividend, and the quotient is written at the top of the number of digits of the dividend. The remainder of each division must be less than the divisor.
(2) Divide 0 by any number that is not 0 to get zero.
(3) If you don't divide by one bit, add a zero placeholder.
(4) See the operation sequence clearly. There is only multiplication and division in the formula, and the calculation is from left to right. If there are brackets, count them first.
Beijing normal university edition: knowledge points of mathematics year, month and day in the third grade of primary school
1, year: normal year: 365 days, leap year: 366 days.
2. Month:
Big month: 1, 3, 5, 7, 8, 10, 65438+February;
Abortion: April, June, September, 165438+ October.
Pingyue (February): 28 days a year on average.
Leap year 29 days
3. Calendar: Learn to look at the calendar and know the date of a certain year, month and day.
4. Clocks and watches: 24-hour chronograph 12 chronograph.
5. Formula:
1 =60 points
1 min =60 seconds
Half an hour =30 minutes
When 60 o'clock = 1
60 seconds = 1 min
30 minutes = half an hour