3rd grade Math Vocabulary

3rd grade Common Core Math Vocabulary
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a.m.
A time between (12:00) midnight and (12:00) noon.
add
To combine, put together two or more quantities.
addend
Any number being added.
Additive Identity Property of 0
When you add zero to a number, the sum is that same number.
algorithm
A step-by-step method for computing.
analog clock
A clock that shows the time by the positions of the hour and minute hand.
angle
Two lines that meet at a common point.
area
The measure, in square units, of the inside of a plane figure.
area model
A model of multiplication that shows each place value product within a rectangle drawing.
arithmetic patterns
A sequence of numbers in which the difference between any two consecutive numbers is the same.

1, 5, 9, 13... is an arithmetic sequence pattern. The difference between any two consecutive numbers is 4.
array
An arrangement of objects in equal rows.
Associative Property of Addition
Changing the grouping of three or more addends does not change the sum.
Associative Property of Multiplication
Changing the grouping of three or more factors does not change the product.
attribute
A characteristic of an object, such as color, shape, size, etc.
bar graph
A graph that uses the height or length of rectangles to compare data.
bar model
A model that uses bars to represent known and unknown quantities and the relationship between these quantities.
base-ten numeral form
A common way of writing a number using digits.
The value of a numeral depends on where it appears in the number.
also known as standard form
base-ten numerals
Any of the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9. The symbols can represent any amount based on a place value system of grouping by tens.

also known as digits
centimeter
A metric unit of length equal to 0.01 of a meter.

100 cm = 1 m
closed shape
A figure that begins and ends at the same point.
column
A vertical arrangement of numbers or information in an array or table.
Commutative Property of Addition
Changing the order of the addends does not change the sum.
Commutative Property of Multiplication
Changing the order of the factors does not change the product.
compare
To decide if one number is greater than, less than, or equal to another number.
compatible numbers
Numbers that are easy to compute mentally and are close in value to the actual numbers.

Compatible numbers can be used when estimating.
compose
To put together 2 or more shapes to create a new shape.
compose
To put together smaller numbers to make larger numbers.
congruent
Having exactly the same size and shape.
counting number
A whole number that can be used to count a set of objects. Counting numbers do not include 0.

(Example: 1, 2, 3, 4...)
customary system
A system of measurement used in the U.S. The system includes
units for measuring length, capacity, and weight.
data
A collection of information.
decagon
A polygon with ten sides.
decompose
To separate into components or basic elements.
denominator
The quantity below the line in a fraction. It tells how many equal parts are in the whole.
difference
The amount that remains after one quantity is subtracted from another.
digit
Any of the symbols
0, 1, 2, 3, 4, 5, 6, 7, 8, or 9.
digital clock
A clock that shows the time with numbers of hours and minutes, usually separated with a colon. (:)
Distributive Property
When one of the factors of a product is a sum, multiplying each addend before adding does not change the product.
divide
To separate into equal groups and find the number in each group or the number of groups.
dividend
A number that is divided by another number.
divisor
The number by which another number is divided.
eighths
The parts you get when you divide something into eight equal parts.
elapsed time
The amount of time that has passed.

(A time interval)
endpoint
A point at either end of a line segment, or a point at one end of a ray.
equal
Having the same value.
equal groups
Groups that contain the same number of objects. Whenever you divide, you separate items into equal groups.
equal parts
Parts of an object or group that have been divided equally into pieces.
equation
A mathematical sentence with an equals sign. The amount on one side of the equals sign has the same value as the amount on the other side.
equivalent fractions
Fractions that have the same value.
estimate
To find a number close to an exact amount; an estimate tells about how much or about how many.
evaluate
To find the value of a mathematical expression.
even number
An even number can be shown as 2 equal parts.

An even number has 0, 2, 4, 6, or 8 in the ones place.
expanded form
A way to write numbers that shows the place value of each digit.
experiment
An activity that has two or more possible results.

Example: pulling marbles from a bag
expression
A mathematical phrase without an equal sign.
fact family
A group of related facts that use the same numbers.

Also called related facts.
factor
The whole numbers that are multiplied to get a product.
foot
A customary unit of length.

1 foot = 12 inches.
fourths
The parts you get when you divide something into 4 equal parts.
fraction
A way to describe a part of a whole or a part of a group by using equal parts.
fraction greater than one
A fraction with the numerator greater than the denominator.
fraction less than one
A fraction with the numerator less than the denominator.
frequency table
A table that uses numbers to record data.
gram
The standard unit of mass in the metric system.
greater than
Greater than is used to compare two numbers when the first number is larger than the second number.
half hour
A unit of time equal to 30 minutes.
halves
The parts you get when you divide something into 2 equal parts.
hexagon
A polygon with six sides.
horizontal bar graph
A graph that uses length of rectangles to compare data.
hour
Units of time.
1 hour = 60 minutes.
24 hours = 1 day.
hundreds
The value of a digit that is the third position from the right when describing whole number place value.
inch
A customary unit of length.

12 inches = 1 foot.
intersecting lines
Lines that cross at a point.
interval
The distance between two points.
inverse operations
Operations that undo each other.
key
A part of a map, graph, or chart that explains what the symbols mean.
kilogram
A metric unit of mass equal to 1000 grams.
length
How long something is. The distance from one point to another.
Length is measured in units such as inches, feet, centimeters, etc.
less than
Less than is used to compare two numbers when the first number is smaller than the second number.
line
A set of connected points continuing without end in both directions.
line plot
A diagram showing frequency of data on a number line.
line segment
A part of a line with two endpoints.
liter
The basic unit of capacity in the metric system.
1 liter = 1,000 milliliters.
mass
The amount of matter in an object. Usually measured by comparing with an object of known mass. While gravity influences weight, it does not affect mass.
meter
A standard unit of length in the metric system.
metric system
A system of measurement based on tens. The basic unit of capacity is the liter. The basic unit of length is the meter. The basic unit of mass is the gram.
midnight
12:00 at night
minute
One sixtieth of an hour or 60 seconds.
multiple
A product of a given whole number and any other whole number.
Multiplicative Identity Property of 1
If you multiply a number by one, the product is the same as that number.
multiply
The operation of repeated addition of the same number.
noon
12:00 in the day
number line
A diagram that represents numbers as points on a line.
numerator
The number written above the line in a fraction. It tells how many equal parts are described in the fraction.
octagon
A polygon with eight sides.
odd number
An odd number cannot be shown as two equal parts.

An odd number has 1, 3, 5, 7, or 9 in the ones place.
ones
A single unit or object.
open shape
A figure that does not begin and end at the same point.
order
A sequence or arrangement of things.

To order fractions, compare two fractions at a time.
Order of Operations
A set of rules that tells the order in which to compute.
p.m.
The time between (12:00) noon and (12:00) midnight.
parallel lines
Lines that are always the same distance apart.
parallelogram
A quadrilateral with two pairs of parallel and congruent sides.
parentheses
Used in mathematics as grouping symbols for operations. When simplifying an expression, the operations within the parentheses are performed first.
partition
An action to divide shapes into smaller parts.
partitive division
A division problem where the number of objects in each group is unknown.

How many in each group?
pattern
repeating or growing sequence or design. An ordered set of numbers or shapes arranged according to a rule.
pentagon
A polygon that has five sides.
perimeter
The distance around a figure.
perpendicular lines
Two intersecting lines that form right angles.
picture graph
A graph that uses pictures or symbols to show data.
place value
The value a digit has because of its place in a number.
plane figure
A two-dimensional figure.
point
The exact location in space represented by a dot.
polygon
A closed plane figure made by line segments.
product
The answer to a multiplication problem.
quadrilateral
A four sided polygon.
quarter hour
A unit of time worth 15 minutes.
quotative division
A division problem where the number of groups is unknown.

How many groups?
quotient
The answer to a division problem.
ray
A part of a line that has one endpoint and goes on forever in one direction.
reasonableness
An answer that is based on good number sense.
rectangle
A quadrilateral with two pairs of congruent, parallel sides and four equal angles.
rectilinear figure
A polygon where all angles are right angles.
regroup
To rearrange the formation of a group.
related facts
Related addition and subtraction facts or related multiplication and division facts.

Also called fact family.
remainder
In whole number division, when you have divided as far as you can without using decimals, what has not been divided yet is called the remainder.
repeated addition
Adding equal groups of objects to find the total amount of objects.
repeated subtraction
Subtracting equal groups to find the total amount of groups.
rhombus
A quadrilateral with all four sides equal in length.
right angle
An angle that forms a square corner.
round a whole number
To find the nearest ten, hundred, thousand, (and so on).
row
A horizontal arrangement of numbers or information in an array or table.
scale (on a graph)
The numbers that show the units used on a graph.
sequence
A set of numbers arranged in a special order or pattern.
side of a polygon
Any of the line segments that form a polygon.
sixths
The parts you get when you divide something into six equal parts.
skip count
Counting by a given number greater than 1.
square
A parallelogram with four equal angles AND four equal sides.
square unit
A unit, such as square centimeter or square inch, used to measure area.
standard form
The common or usual way of writing a number using digits.

Also called base-ten numeral form.
subtract
An operation that gives the difference between two numbers.

Subtraction can be used to compare two numbers, or to find out how much is left after some is taken away.
sum
The answer to an addition problem.
survey
A way to gather data by asking questions.
tally table
A table that uses tally marks to record data.
tens
Sets of ten ones.

Examples: 10, 20, 30, 40, 50, 60, 70, 80, or 90
thirds
The parts you get when you divide something into 3 equal parts.
tiling
A pattern of shapes repeated to fill a plane. The shapes do not overlap and there are no gaps.
time interval
A duration of a segment of time.

Also known as elapsed time
trapezoid
A quadrilateral with one pair of parallel sides and one pair of sides that are not parallel.
triangle
A polygon with three sides and three angles.
two-dimensional
Having length and width. Having area, but not volume.

Also called a plane figure.
unit fraction
A fraction that has 1 as its numerator.

A unit fraction names 1 equal part of a whole.
unit square
A square with side lengths of 1 unit each. It has an area of 1 square unit.
variable
A letter or symbol that represents a number.
Venn diagram
A drawing with circles or rings to show how sets of objects are related.
vertex (plural - vertices)
A point at which two or more sides of a geometric figure meet.
vertical bar graph
A graph that uses height of rectangles to compare data.
volume (liquid)
The number of cubic units it takes to fill a figure.
whole
All of an object, a group of objects, shape, or quantity.
whole numbers
Whole numbers are zero and the counting numbers 1, 2, 3, 4, 5, 6, and so on.

If a number has a negative sign, a decimal point, or a part that's a fraction, it is not a whole number.
width
One dimension of a 2-dimensional or 3-dimensional figure.
word form
A way of using words to write a number.

Also called number names.
yard
A customary unit of length.

1 yard = 3 feet
or 36 inches
Zero Property of Multiplication
The product of any number and zero is zero.
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