An angle that measures less than 90 degrees.

A figure made up of 2 rays that share the same starting point.

The same denominator in two or more fractions. Example, and have the common denominator 4.

A whole number with more than one factor pair.

A way to write tenths, hundredths, and other decimal fractions as numerals with digits and a decimal point. The digits to the left of the decimal point show the whole-number part of the number. The digits to the right of the decimal point show the fractional part less than 1.

Examples:

written in decimal notation is 0.3.

written in decimal notation is 0.25.

written in decimal notation is 1.7.

written in decimal notation is 2.07.

A unit of rotation used to measure angles. Each degree is of a circle.

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

The number being divided. Example: When 37 is divided by 5, we call 37 the dividend. 

The number we are dividing by, which can represent the size of the groups or the number of groups.  Example: When 37 is divided by 5, we call 5 the divisor. 

Fractions that have the same size and describe the same point on the number line. Example:  and  are equivalent fractions.

A way of writing a number as a sum of the values of the digits.

Example: 482 written in expanded form is  .

Two whole numbers that multiply to result in that number. Example: 5 and 4 are a factor pair of 20.

Lines that cross.

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

A line that divides a figure into 2 halves that match up exactly when the figure is folded along the line.

A part of a line with 2 endpoints and all of the points in between them.

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

The result of multiplying that number by a whole number. 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.

An angle that measures greater than 90 degrees.

Lines that never intersect.

Intersecting lines that create 4 right angles.

A location along a line or in space.

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

 A flat shape with 4 straight sides and 4 angles.

The result of dividing one number by another.

A part of a line that starts at 1 point and goes on infinitely in 1 direction.

A quadrilateral with 2 pairs of parallel sides and 4 right angles.

The amount left over when we divide a number. The amount is not enough to put into equal groups or to make a new group.

A quadrilateral with 4 equal sides.

An angle that measures 90 degrees.

A triangle with a 90-degree angle.

To say which number a given number is closer to. Example: For 182, the number 180 is the closest multiple of 10, and 200 is the closest multiple of 100. We can round 182 to 180 (if rounding to the nearest ten) or 200 (if rounding to the nearest hundred).

A quadrilateral with 4 equal sides and 4 right angles.

A set of steps used to add or subtract numbers by place value. Write the numbers vertically with digits lined up by place value. Add or subtract the digits in each place value, starting with the least place value. Compose or decompose units, as needed in each place value.

An angle that measures 180 degrees.

When the parts of a figure can match up exactly after it is folded or turned.

A flat shape with 3 straight sides and 3 angles.

The point that 2 rays share when they form an angle.