3rd Grade Math Concepts

Segment
A segment is a portion of a line and it has 2 endpoints.

Identity property of addition
Any number plus zero is equal to the number

5 + 0 = 5
2 + 0 = 2

Parallel lines
Parallel lines never meet no matter how long you extend the lines

1 inch
1 inch is about the size of a quarter.
1 foot = 12 inches

Division
12  ÷  3
Share 12 soccer balls with 3 friends equally.
Just make 3 equal groups with 12.
The number of balls in each group is the answer.

Gram/ kilogram
1 gram is about the mass of 1 paperclip.
1000 grams  = 1 kg
About 1000 paperclips will be equivalent to 1 kg.
1 large book could also have a mass of 1 kg.

Expanded form
The expanded form shows the place value of each digit. 

478 = 400  + 70 + 8

Divisor
The number that is used to divide. For example if 6 is used to divide 48, 6 is the divisor.

Factors
A factor is a number that is multiplied by one or more numbers. For example, in 3 × 5, 5 is a factor since 5 is multiplied by 3. By the same token, 3 is also a factor since it is multiplied by 5.

Area
The amount of space inside a 2-dimensional object.

Word form of numbers

For example, the word form of 24652 is  "twenty four thousand, six hundred fifty-two"

Addition algorithm

Commutative property of multiplication
The order in which two numbers are multiplied in a multiplication problem does not matter.
6 × 2 = 2 × 6

Identity property of multiplication
Any number multiplied by one is equal to the number.

5 × 1 = 5
2 × 1 = 2

Commutative property of addition.
The order in which two numbers are added in an addition problem does not matter.

1  + 2   =   2 + 1 
       =     3

Perimeter
The perimeter is the distance around a closed figure.
Perimeter = 2 cm + 2 cm + 4 cm + 3 cm
                  = 4 cm + 4 cm + 3 cm
                  = 8 cm + 3 cm
                  = 11 cm

Fact family
A group of 3 numbers that are related in a special way. Doing math with 2 numbers always give the last number.

Pentagon
A figure that has 5 sides is called a pentagon.

Dividend
The number that will be divided is the dividend. For example, if 48 is divided by 6, 48 is the dividend.

Point
A point is an exact location on a piece of paper represented with a single dot 

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Standard form
The standard form is the base 10 numeration system or the usual way of writing numbers.

24577

Unit fraction
A fraction whose numerator is equal to 1. The denominator can be equal to any number.

Round a number

28 is closer to 30, so the nearest 10 is 30.
28 rounded to the nearest 10 is 30.

23 is closer to 20, so the nearest 10 is 20.
23 rounded to the nearest 10 is 20

Product
The answer to a multiplication problem. For example, the product of 3 times 5 is 15.

Fraction
Divide a rectangle into 4 equal smaller rectangles.
Take 1 rectangle out of 4. The fraction is 1/4.

Quotient
The answer to a division problem. For example, when you divide 48 by 6, the answer is 8. So 8 is the quotient.

Equivalent fractions.
Equivalent fractions are fractions that have the same value, but have different numerators and denominators.

Order of operations
The proper way to do the math or rule to follow when a math problem has a combination of different operators (+, -, ×, etc.). 

Three fourths
The circle has 4 parts. 3 parts of the circle are shaded.
The numerator is 3 and the denominator is 4.

Algorithm for adding 28 and 14