an angle that measures less than 90 degrees and greater than 0 degrees.

Algebraic rule

a mathematical expression that contains variables and describes a pattern or relationship

Angle

the shape made by two rays extending from a common end point, the vertex. Measures of angles are described using the degree system.

Area

the inside region of a two-dimensional figure measured in square units (e.g., a rectangle with sides of 4 units by 6 units contains 24 square units or has an area of 24 square units).

Axes (of a graph)

the horizontal and vertical number lines used in a rectangular graph or coordinate grid system.

Bar graph

a graph that uses bars to display data.

Base

the line or plane upon which a figure is thought to rest.

Capacity

the amount of space that can be filled. Both capacity and volume are used to measure three- dimensional spaces; however, capacity usually refers to fluids, whereas volume usually refers to solids.

Closed figure

a two-dimensional figure whose beginning and ending points meet, such that the plane in which the figure lies is divided into two parts - the part inside the figure and the part outside the figure (e.g., circles, squares, rectangles).

Composite number

a whole number that has more than two factors.

Concrete representations of numbers

having a definite form or relating to an actual object.

Congruent

a term describing figures or objects that are the same shape and size.

Coordinate grid or system

a network of evenly spaced, parallel, horizontal and vertical lines especially designed for locating points, displaying data, or drawing maps.

Customary units

the units of measure developed and used in the United States.
Customary units for length are inches, feet, yards, and miles.
Customary units for weight are ounces, pounds, and tons.
Customary units for volume are cubic inches, cubic feet, and cubic yards.
Customary units for capacity are fluid ounces, cups, pints, quarts, and gallons.

Decimal number

any number written with a decimal point in the number. A decimal number falls between two whole numbers (e.g., 1.5 falls between 1 and 2). Decimal numbers smaller than 1 are sometimes called decimal fractions (e.g., five-tenths is written 0.5).

Direct measure

obtaining the measure of an object by using measuring devices, either standard devices of the customary or metric systems, or nonstandard devices such as a paper clip or pencil.

Divisible

a term describing a number capable of being divided into equal parts without a remainder.

Effects of operation

the results of applying an operation to given numbers (e.g., adding two whole numbers results in a number greater than or equal to the original numbers).

Empirical probability

the likelihood of an event happening that is based on experience and observation rather than on theory.

Equation

a mathematical sentence (e.g., 2x = 10) that equates one expression (2x) to another expression (10).

Equivalent forms of a number

the same number expressed in different forms (e.g., 3/4, 0.75, 75%).

Estimation

the use of rounding and/or other strategies to determine a reasonably accurate approximation, without calculating an exact answer.

Evaluate an algebraic expression

substitute numbers for the variables and follow the operation symbols to find the numerical value of the expression.

Explain in words

directions requesting a written description of the procedures for finding the solution to the problem presented.

Expression

a collection of numbers, symbols, and/or operation signs that stands for a number.

Face

one of the plane surfaces bounding a three-dimensional figure (a side).

Factor

a number or expression that divides exactly another number (e.g., 1,2,4,5,10, and 20 are factors of 20).

Flip

a transformation that produces the mirror image of a geometric figure. Also called a Reflection.

Fraction

any part of a whole is called a fraction (e.g., one-half written in fractional form is 1/2).

Function

the relationship between two sets (e.g., sets of numbers) in which each element of one set has one assigned element in the other set. See Pattern.

Grid

a network of evenly spaced, parallel, horizontal and vertical lines.

Height

a line segment extending from the vertex or apex of a figure to its base and forming a right angle with the base or basal plane.

Indirect measure

the measurement of an object through the known measure of another object.

Inequality

a sentence that states one expression is greater than, great than or equal to, less than, less than or equal to, or not equal to, another expression (e.g., a does not equal 5 or x is less than 7).

Intersection

the point at which two lines meet.

Labels (for a graph)

the titles given to a graph, the axes of a graph, or to the scales on the axes of the graph.

Length

a one-dimensional measure that is the measureable property of line segments.

Likelihood

the chance that something is likely to happen. See probability.

Line

a straight line that is endless in length.

Line graph

a graph that displays data using connected line segments.

Line Segment

a portion of a line that has a defined beginning and end. (e.g., the line segment AB is between point A and point B).

Mean

the average of a set of numbers found by adding the numbers in a set and dividing by the number of addends.

Median

the middle point of a set of ordered numbers where half of the numbers are above the median and half are below it.

Metric units

the units of measure developed in Europe and used in most of the world. Like the decimal system, the metric system uses the base 10. Metric units for length are millimeters, centimeters, meters, and kilometers.
Metric units for weight are milligrams, grams, and kilograms.
Metric units for volume are cubic millimeters, cubic centimeters and cubic meters.
Metric units for capacity are milliters, centiliters, liters, and kiloliters.

Mode

the score or data point found most often in a set of numbers.

Multiples

the numbers that result from multiplying a given number by the set of whole numbers (e.g., the multiples of 15 are 0, 15, 30, 45, 60, 75, etc.).

Nonstandard units of measure

objects such as blocks, paper clips, crayons, or pencils that can be used to obtain a measure.

Number line

a line on which numbers can be written or visualized.

Obtuse angle

an angle with a measure of more than 90 degrees but less than 180 degrees.

Operation

any mathematical process, such as addition, subtraction, multiplication, division, raising to a power, or finding the square root.

Ordered pair

a pair of numbers that gives the coordinates of a point on a grid.

Organized data

data arranged in a display that is meaningful and assists in the interpretation of the data.

Parallel lines

two lines in the same plane that never meet. Also, lines with equal slopes.

Pattern (relationship)

a predictable or prescribed sequence of numbers, objects, etc. Patterns and relationships may be described or presented using manipulatives, tables, graphics (pictures or drawings), or algebraic rules (functions). Also called a Relation.

Percent

a special-case ratio in which the second term is always 100. The ratio is written as a whole number followed by a percent sign. (e.g., 25% means the ratio of 25 to 100).

Perimeter

the distance around a figure.

Perpendicular

a term describing two lines or line segments that cross to form a right angle.

Place Value

the position of a single digit in a whole number or decimal number containing one or more digits.

Plane

an undefined, two-dimensional (no depth) geometric surface that has no bounderies specified. A plane is determined by defining points or lines existing on the plane.

Plane figure

a two-dimensional figure that lies entirely within a single plane.

Point

a location in space that has no discernible length or width.

Polygon

a closed plane figure whose sides are straight lines that are connected end-point to end-point.

Prime number

any whole number with only two factors, 1 and itself (e.g., 2, 3, 5, 7, 11, etc.).

Probability

a measure of the likelihood that a given event will occur; expressed as a number between 0 and 1 (see Empirical probability and Theoretical/expected probability).

Range

the lowest value (L) in a set of numbers through the highest value (H) in the set. When the width of the range is expressed as a single number, the range is calculated as the difference between the highest and lowest values. More advanced presentations show the range calculated as (H - L + 1). The result of either calculation would be considered correct.

Ratio

the quotient of two numbers used to compare two quantities (e.g., the ratio of 3 to 4 is 3/4.)

Ray

a portion of a line that begins at a point and goes on forever in one direction.

Reflection

see Flip

Regular polgyon

a polygon that is both equilateral and equiangular.

Relation (relationship)

see Pattern

Relative size

the size of one number in comparison to the size of another number or numbers.

Right angle

an angle whose measure is exactly 90 degrees.

Rotation

a transformation of a figure by turning it about a center point or axis. The amount of rotation is usually expressed in the number of degrees (e.g., a 90 degree rotation). Also called a Turn.

Rule

a mathematical expression that describes a pattern or relationship, or a written description of the pattern or relationship.

Scale model

a model or drawing based on a ratio of the dimensions for the model and the actual object it represents (e.g., a map).

Scales

the numeric values assigned to the axes of a graph.

Side

the edge of a geometric figure (e.g., a triangle has three sides).

Similar figures

figures that are the same shape, having corresponding congruent angles, and have corresponding sides that are proportional in length.

Similarity

a term describing figures that are the same shape but are not necessarily the same size or in the same position.

Slide

to move along in constant contact with the surface in a vertical, horizontal, or diagonal direction. Also called a Translation.

Spatial relationships

relationships of figures existing or happening in space.

Standard units of measure

accepted measuring devices and units of the customary or metric system.

Straight angle

an angle whose measure is exactly 180 degrees.

Symbolic expression

a symbol or set of symbols expressing a mathematical quantity or operation
(e.g., 2x is equal to two times x).

Symmetry

a term describing the result of a line drawn through the center of a figure such that the two halves are congruent.

Theoretical/expected probability

the likelihood of an event happening based on theory rather than on experience and observation.

Transformation

an operation on a geometric figure by which another image is created. Common transformations include flips, slides, and turns.

Translation

see Slide.

Tree Diagram

a diagram in which all the possible outcomes of a given event are displayed.

Turn

see Rotation.

Unorganized data

data that are presented in a random manner.

Variable

any symbol that could represent a number.

Vertex

the common endpoint from which two rays begin (i.e., the corner of an angle) or the point where two lines intersect: the point on a triangle or pyramid opposite to and farthest from the base.

Volume

the amount of space occupied in three dimensions and expressed in cubic units. Both capacity and volume are used to measure empty spaces; however, capacity usually refer to fluids, whereas volume usually refers to solids.

Weight

measure that represents the force that attracts an object to the center of Earth.

Whole numbers

the numbers in the set {0, 1, 2, 3, 4, ...}