acute angle
Unit 7 Lesson 12

An angle that measures less than 90 degrees.

angle
Unit 7 Lesson 5

A figure made up of two rays that share the same endpoint.

common denominator
Unit 2 Lesson 15

The same denominator in two or more fractions. For instance, and have a common denominator.

composite number
Unit 1 Lesson 3

A whole number with more than 1 factor pair.

denominator
Unit 2 Lesson 1

The bottom part of a fraction that tells how many equal parts the whole was partitioned into.

dividend
Unit 6 Lesson 13, Unit 6 Lesson 20

The number being divided. For example, when 37 is divided by 5, we call 37 the dividend.

equivalent fractions
Unit 2 Lesson 4

Fractions that have the same size and describe the same point on the number line. For example, and are equivalent fractions.

expanded form
Unit 4 Lesson 8, Unit 4 Lesson 11

A specific way of writing a number as a sum of hundreds, tens, and ones.

Expanded form writes a number as a sum of the value of each digit. Example: 482 written in expanded form is .

factor pair of a whole number
Unit 1 Lesson 2

A pair of whole numbers that multiply to result in that number. For example, 5 and 4 are a factor pair of 20.

intersecting lines
Unit 7 Lesson 3, Unit 7 Lesson 5

Lines that cross.

line
Unit 7 Lesson 2

A set of points that are arranged in a straight way and extend infinitely in opposite directions.

line of symmetry
Unit 8 Lesson 4

A line that divides a figure into two halves that match up exactly when the figure is folded along the line.

mixed number
Unit 3 Lesson 8, Unit 3 Lesson 14

A number expressed as a whole number and a fraction less than 1.

multiple of a number
Unit 1 Lesson 1

The result of multiplying that number by a whole number. For example, 18 is a multiple of 3, because it is a result of multiplying 3 by 6.

numerator
Unit 2 Lesson 1

The top part of a fraction that tells how many of the equal parts are being described.

obtuse angle
Unit 7 Lesson 12

An angle that measures greater than 90 degrees.

parallel lines
Unit 7 Lesson 3, Unit 7 Lesson 5

Lines that never intersect.

perpendicular lines
Unit 7 Lesson 10

Lines that intersect creating right angles.

point
Unit 7 Lesson 1

A location along a line or in space.

prime number
Unit 1 Lesson 3

A whole number that is greater than 1 and has exactly one factor pair: the number itself and 1.

ray
Unit 7 Lesson 2

A line that ends at one point and goes on in the other direction.

remainder
Unit 6 Lesson 20

The number left over when we take away as many equal groups as we can from a number.

right angle
Unit 7 Lesson 8

An angle with a measurement of 90 degrees.

rounding
Unit 4 Lesson 16

A formal way to say which number a given number is closer to. For example, for 182, the number 180 is the closest multiple of ten and 200 is the closest multiple of a hundred. We can round 182 to 180 (if rounding to the nearest ten) or 200 (if rounding to the nearest hundred).

segment or line segment
Unit 7 Lesson 1

A part of a line with two endpoints.

straight angle
Unit 7 Lesson 12

An angle that measures 180 degrees.

symmetry
Unit 8 Lesson 4, Unit 8 Lesson 6

A figure has symmetry if its parts can match up exactly when the figure is folded or rotated.

vertex
Unit 7 Lesson 5

The point where the two rays meet.