acute angle
Unit 7 Lesson 12

An angle that measures less than 90 degrees.

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.

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.

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.

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.

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.

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.

Lines that never intersect.

perpendicular lines
Unit 7 Lesson 10

Lines that intersect creating right angles.

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.

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

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.

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.

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

The point where the two rays meet.