acute angle

An angle with a measure less than 90°.

add

To combine, put together two or more quantities.

addend

Any number being added.

algorithm

A step-by-step method for computing.

angle

Two rays that share an endpoint.

angle measure

The measure of the size of an angle. It tells how far one side is turned from the other side. A one degree angle turns through 1/360 of a full circle.

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.

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.

benchmark fraction

Fractions that are commonly used for estimation.

capacity

Capacity refers to the amount of liquid a container can hold.

centimeter (cm)

A metric unit of length equal to 0.01 of a meter.

circle

A plane figure with all points the same distance from a fixed point called a center.

classify

To sort into categories or to arrange into groups by attributes.

common denominator

For two or more fractions, a common denominator is a common

multiple of the denominators.

multiple of the denominators.

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.

compose

To put together components or basic elements.

composite number

A number greater than 0 that has more than two different factors.

congruent

Having exactly the same size and shape.

cup (c)

A customary unit of capacity.

1 cup = 8 fluid ounces.

1 cup = 8 fluid ounces.

customary system

A system of measurement used in the U.S. The system includes

units for measuring length, capacity, and weight.

units for measuring length, capacity, and weight.

data

A collection of information gathered for a purpose. Data may be in the form of either words or numbers.

decimal

A number with one or more digits to the right of a decimal point.

decimal notation

A number containing a decimal point.

decimal point

A dot (.) separating the whole number from the fraction in decimal notation.

decompose

To separate into components or basic elements.

degree (angle measure)

A unit for measuring angles. Based on dividing one complete circle into 360 equal parts.

denominator

The quantity below the line in a fraction. It tells how many equal parts are in the whole.

digit

Any of the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

difference

The amount that remains after one quantity is subtracted from another.

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.

endpoint

A point at either end of a line segment, or a point at one end of a ray.

equal

Having the same value.

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.

expanded form

A way to write numbers that shows the place value of each digit.

expression

A mathematical phrase without an equal sign.

fact family

A group of related facts that use the same numbers.

Also called related facts.

Also called related facts.

factor

The whole numbers that are multiplied to get a product.

factor pairs

A set of two whole numbers when multiplied, will result in a given product.

foot (ft)

A customary unit of length.

1 foot = 12 inches.

1 foot = 12 inches.

formula

A rule that is written as an equation.

fracton

A way to describe a part of a whole or a part of a group by using equal parts.

function table

A table that lists pairs of numbers that follow a rule.

gallon (gal)

A customary unit of capacity.

1 gallon = 4 quarts.

1 gallon = 4 quarts.

gram (g)

The standard unit of mass in the metric system. 1,000 grams = 1 kilogram

greater than

Greater than is used to compare two numbers when the first number is larger than the second number.

hour (hr)

A unit of time.

1 hour = 60 minutes.

24 hours = 1 day.

1 hour = 60 minutes.

24 hours = 1 day.

hundredth

One of the equal parts when a whole is divided into 100 equal parts.

hundredths

In the decimal numeration system, hundredths is the name of the next place to the right of tenths.

Identity Property of Addition

If you add zero to a number, the sum is the same as that number.

Identity Property of Multiplication

If you multiply a number by one, the product is the same as that number.

improper fraction

A term for a fraction whose numerator is greater than or equal to its denominator.

inch (in)

A customary unit of length.

12 inches = 1 foot.

12 inches = 1 foot.

intersecting lines

Lines that cross at a point.

inverse operations

Operations that undo each other.

kilogram (kg)

A metric unit of mass equal to 1000 grams.

kilometer (km)

A metric unit of length equal to 1000 meters.

length

How long something is. The distance from one point to another.

Length is measured in units such as inches, feet, centimeters, etc.

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.

like denominators

Denominators in two or more fractions that are the same.

line

A set of connected points continuing without end in both directions.

line of symmetry

A line that divides a figure into two congruent halves that are mirror images of each other.

line plot

A diagram showing frequency of data on a number line.

line segment

A part of a line with two endpoints.

liter (L)

The basic unit of capacity in the metric system.

1 liter = 1,000 milliliters.

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 (m)

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.

mile

A customary unit of length.

1 mile = 5,280 feet

1 mile = 5,280 feet

milliliter (mL)

A metric unit of capacity.

1,000 milliliters = 1 liter.

1,000 milliliters = 1 liter.

millimeter (mm)

A metric unit of length. 1,000 millimeters = 1 meter

minute (min)

One sixtieth of an hour or 60 seconds.

mixed number

A number that has a whole number (not 0) and a fraction.

multiple

A product of a given whole number and any other whole number.

multiply

The operation of repeated addition of the same number.

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.

obtuse angle

An angle with a measure greater than 90º but less than 180º.

Order of Operations

A set of rules that tells the order in which to compute.

ounce (oz)

A customary unit of weight equal to one sixteenth of a pound. 16 ounces = 1 pound.

parallel lines

Lines that are always the same distance apart. They do not intersect.

parentheses

( )

( )

Used in mathematics as grouping symbols for operations. When simplifying an expression, the operations within the parentheses are performed first.

pattern

A repeating or growing sequence or design. An ordered set of numbers or shapes arranged according to a rule.

perimeter

The distance around the outside of a figure.

period

In a large number, periods are groups of 3 digits separated by commas or by spaces.

perpendicular lines

Two intersecting lines that form right angles.

pint (pt)

A customary unit of capacity.

1 pint = 2 cups

1 pint = 2 cups

place value

The value of the place of a digit in a number.

plane figure

A two-dimensional figure.

point

The exact location in space represented by a dot.

pound (lb)

A customary unit of weight.

1 pound = 16 ounces.

1 pound = 16 ounces.

prime number

A whole number greater than 0 that has exactly two different factors, 1 and itself.

product

The answer to a multiplication problem.

protractor

A tool used to measure and draw angles.

quart (qt)

A customary unit of capacity.

1 quart = 2 pints

or

1 quart = 4 cups

1 quart = 2 pints

or

1 quart = 4 cups

quotient

The answer to a division problem.

range

The difference between the greatest number and the least number in a set of data.

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.

related facts

Related addition and subtraction facts or related multiplication and division facts.

Also called fact family.

Also called fact family.

remainder

The amount left over when one number is divided by another.

right angle

An angle that measures exactly 90º.

right triangle

A triangle that has one 90º angle.

round a whole number

To find the nearest ten, hundred, thousand, (and so on).

second (sec)

(unit of time)

(unit of time)

One sixtieth of a minute. There are 60 seconds in a minute.

sequence

A set of numbers arranged in a special order or pattern.

simplest form

When a fraction is expressed with the fewest possible pieces, it is in simplest form. (Also called lowest terms.)

simplify

To express a fraction in simplest form.

square unit

A unit, such as square centimeter or square inch, used to measure area.

standard form

A common or usual way of writing a number using digits.

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.

tenth

One of the equal parts when a whole is divided into 10 equal parts.

time interval

A duration of a segment of time.

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.

unlike denominators

Denominators that are not equal.

variable

A letter or symbol that represents a number.

vertex

The point at which two line segments, lines, or rays meet to form an angle.

volume

The number of cubic units it takes to fill a figure.

weight

The measure of how heavy something is.

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.

word form

A way of using words to write a number.

yard (yd)

A customary unit of length.

1 yard = 3 feet or 36 inches.

1 yard = 3 feet or 36 inches.

Zero Property of Multiplication

The product of any number and zero is zero.