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Math Glossary

Algorithm- a set of step-by-step instructions for doing something, such as carrying out a computation or solving a problem.

Angle- a figure that is formed by two rays or two line segments that have the same endpoint

Area- the amount of surface inside a shape. Area is measured in square units, such as square inches or square centimeters.

Array- an arrangement of objects into rows and columns that form a rectangle. All rows and columns must be filled. Each row and columns must be filled. Each row has the same number of objects, and each column has the same number of objects.

Bar graph- a graph that uses horizontal or vertical bars to represent data.

Base- a name used for a side of a polygon or a face of a 3-dimensional figure.

Capacity- (1) the amount a container can hold. The volume of a container. Capacity is usually measured in units such as gallons, pints, cups, and liters. (2) The heaviest weight a scale can measure.

Change number story- a number story in which an amount is increased (a change –to- more story) or decreased (a change-to-less story). A change diagram can be used to keep track of the numbers and missing information in such problems.

Circumference- the distance around a circle; the perimeter of a circle.

Comparison number story- a number story in which two quantities are compared. A comparison diagram can be used to keep track of the numbers and missing information in such problems.

Composite number- a counting number that has more than two different factors. For example, 4 is a composite number because it has three factors: 1, 2, and 4.

Cone- a solid that has a circular base and a curved surface that ends at a point called the apex.

Congruent figures- figures that have the same shape and the same size. Two figures on a flat surface are congruent if they match exactly when one is placed on top of the other.

Coordinate grid- a grid formed by drawing two number lines that form right angles. The number lines intersect at their zero points. You can use ordered pairs of numbers to locate points on a grid. (The numbers in each pair are called coordinates.) Maps are often based on coordinate grids.

Coordinates- see ordered pair

Counting numbers- the numbers used in counting 1,2,3,4 and so on. Zero is sometimes thought of as a counting number.

Cylinder- a solid that has two bases that are parallel and the same size. The bases are connected by a curved surface. A soup can is shaped like a cylinder.

Data- information that is collected by counting, measuring, asking questions, or observing.

Decimal- a number, such as 23.4, that contains a decimal point. Money amounts, such as \$6.58, are decimal numbers. The decimal point in money separates the dollars from the cents.

Decimal point- a dot used to separate the ones place from the tenths place in decimal numbers.

Degree- (1) a unit of measure for angles. (2) A unit of measure for temperature. In both cases, a small raised circle is used to show degrees.

Denominator- the number below the line in a fraction. For example, in ¾, 4 is the denominator.

Diameter- (1) A line segment that goes through the center of a circle and has endpoints on the circle. (2) The length of this line segment. The diameter of a sphere is defined in the same way. The diameter of a circle or sphere is twice the length of its radius.

Digits- the symbols 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 that are used to write any number in our number system.

Edge- a line segment or curve where the surfaces of a solid meet.

Endpoint- a point at the end of a line segment or ray. A line segment is named using the letter labels of its endpoints. A ray is named using the letter labels of its endpoint and another point on the ray.

Equal groups- collections or groups of things that all contain the same number of things. For example, rows of chairs with 6 chairs per row are equal groups.

Equilateral triangle- a triangle with all three sides equal in length. In an equilateral triangle, all three angles have the same measure.

Equivalent names- different ways of naming the same number

Estimate- an answer that should be close to an exact answer. To estimate means to give an answer that should be close to an exact answer.

Even number- a counting number that can be divided by 2 with no remainder. The even numbers are 2,4,6,8 and so on.

Event – something that happens. Tossing heads with a coin is an event. Rolling a number smaller than 5 with a die is an event. The probability of an event is the chance that the event will happen.

Explorations- In First through Third Grade Everyday Mathematics, independent or small-group activities that focus on one or more of the following: concept development, manipulatives, data collection, problem solving, games, and skill reviews.

Face- a flat surface on the outside of a solid.

Fact Family- (1) a set of related addition and subtraction facts. For example, 5+6=11, 6+5=11, 11-5=6, and 11-6=5 are a fact family. (2) A set of related multiplication and division faces.

Fact triangles- cards with a triangle shape that show fact families. Fact triangles are used like flash cards to help you memorize basic addition, subtraction, multiplication, and division facts.

Factor- (1) any of the numbers that are multiplied to find a product. (2) A number that divides another number evenly.

Facts table- a chart with rows and columns that shows all of the basic addition and subtraction facts, or all of the basic multiplication and division facts.

Fraction- a number in the form ½. The number 1 is called the numerator and can be any counting number or 0 the number 2 is called the denominator and can be any counting number except 0. One use for fractions is to name part of a whole or part of a collection.

Frames and Arrows- A diagram used in Everyday Mathematics to show a number pattern sequence.

Function machine- an imaginary machine used in Everyday Mathematics to change numbers according to a given rule.

Lattice method- one method for solving multiplication problems.

Line graph- a graph that uses line segments to connect data points. Line graphs are often used to show how something has changed over a period of time.

Line plot- a sketch of data that uses Xs, checks, or other marks above a number line to show how many times each value appears in the set of data.

Line segment- a straight path joining two points. The two points are called endpoints of the segment.

Line symmetry- a figure has line symmetry if a line can divide it into two parts that look like mirror images of each other. The two parts look alike but face in opposite directions. The dividing line is called the line of symmetry.

Math boxes- in Everyday Mathematics a collection of problems to practice skills. Math boxes for each lesson are in the math journal.

Math Message- in Everyday Mathematics, an introductory activity that children complete before the lesson starts.

Maximum- the largest amount. The largest number in a set of data.

Mean- the average number in a set of data. The mean is found by adding all of the data values and then dividing by the number of numbers in the set of data.

Median- the middle number in a set of data when the numbers are put in order from smallest to largest, or from largest to smallest. The median is also known as the middle number or middle value.

Metric system- a measuring system that is used by scientists everywhere, and in most countries of the world except the United States. The metric system is a decimal system. It is based on multiples of 10.

Minimum- the smallest amount. The smallest number in a set of data.

Mode- the number or value that occurs most often in a set of data.

Name-collection box- in Everyday Mathematics, a place to write equivalent names for the same number.

Negative number- a number that is less than zero. A number to the left of zero on a horizontal number line. A number below zero on a vertical number line. The symbol- may be used to write a negative number. For example, “negative 5” is usually written as -5.

Number grid- a table with rows and columns that lists numbers in order. A monthly calendar is a number grid.

Number line- a line with numbers marked in order on it.

Number model- a group of numbers and symbols that shows how a number story can be solved. For example, 10-6=4 and 10-6 are each number models for the following story: I had 10 cookies. I gave 6 away. How many did I have left?

Numerator- the number above the line in a fraction. For example, in ¾, 3 is the numerator.

Odd number- a counting number that cannot be exactly divided by 2. When an odd number is divided by 2, there is a remainder of 1. The odd numbers are 1, 3, 5, and so on.

Ordered pair- a pair of numbers, such as (5, 3) or (1, 4), used to find a location on a coordinate grid. The numbers in an ordered pair are called coordinates.

Parallel- Always the same distance apart and never meeting or crossing each other, no matter how far extended. Line segments are parallel if they are parts of lines that are parallel. The bases of a prism parallel. The bases of a cylinder are parallel.

Parallelogram- a 4-sided polygon whose opposite sides are parallel. The opposite sides of a parallelogram are also the same length. And the opposite same length. And the opposite angles in a parallelogram have the same measure.

Partial-products method- one method for solving multiplication problems.

Partial-sums method- one method for solving addition problems

Parts-and-total number story- a number story in which two parts are combined to find a total. A parts-and-total diagram can be used to keep track of the numbers and missing information in such problems.

Pattern-Block Template- In first through third grade Everyday Mathematics, a sheet of plastic with geometric shapes cut out, used to draw patterns and design.

Percent- per hundred, for each hundred, or out of a hundred.

Perimeter- the distance around a polygon or other shape. The perimeter of a circle is called a circumference.

Pictograph- a graph that uses pictures or symbols to show numbers. The key for a pictograph tells what each picture or symbol is worth.

Place value- a system for writing numbers in which the value of a digit depends on its place in the number

Polygon- a closed figure on a flat surface that is made up of line segments joined end to end. The line segments make one closed path and may not cross

Polyhedron- a solid whose surface (called faces) are all flat and formed by polygons. A polyhedron does not have any curved surfaces

Positive Number- a number that is greater than zero. A number to the right of zero on a horizontal number line. A number above zero on a vertical number line. A positive number may be written using the + symbol, but is usually written without it

Prime number- a counting number that has exactly two different factors that are counting numbers: itself and 1. For example, 5 is a prime number because its only factors are 5 and 1. The number 1 is not a prime number because that number has only a single factor, the number 1 itself.

Prism- a polyhedron that has two parallel bases that are formed by polygons with the same size and shape. The other faces connect the bases and are all shaped like parallelograms. These other faces are often rectangles. Prisms take their names from the shape of their bases.

Probability- a number from 0 through 1 that tells the chance that an event will happen. The closer a probability is to 1; the more likely the event is to happen

Product- the result of multiplying two numbers, called factors.

Pyramid- a polyhedron is which one face, the base, may have any polygon shape. All of the other faces have triangle shapes and come together at a vertex called the apex. A pyramid takes its name from the shape of its base.

Quadrangle- a polygon that has four angles. Same as quadrilateral.

Quadrilateral- a polygon that has four sides. Same as quadrangle.

Quotient- the result of dividing one number by another number.

Radius (plural: radii) - (1) A line segment from the center of a circle to any point on the circle. (2) The length of this line segment. The radius of a sphere is defined in the same way. The radius of a circle or sphere is one-half the length of its diameter.

Range- the difference between the largest (maximum) and the smallest (minimum) numbers in a set of data.

Ray- a straight path that has one endpoint and goes on forever in one direction.

Regular polygon- a polygon whose sides all have the same length and whose angles (inside the polygon) all have the same size

Remainder- the amount left over when things are divided or shared equally. Sometimes there is no remainder.

Rhombus- a parallelogram with all four sides the same length. Every square is a rhombus, but not all rhombuses are squares.

Right angles- a 90 degree angle. The sides of a right angle from a square corner.

Right triangle- a triangle that has one 90 degree angle.

Round- to adjust a number to make it easier to work with. Often, numbers are rounded to the nearest 10, 100, 1,000, and so on. For example, 864 rounded to the nearest hundred is 900

Scale drawing- a drawing that represents an actual object or region, but is a different size. Maps are scale drawings. Architects and builders use scale drawings.

Side- (1) One of the rays or segments that make up an angle. (2) One of the line segments of a polygon. (3) One of the faces of a solid figure.

Solids- three dimensional shapes, such as prisms, pyramids, cylinders, cones, and spheres.

Standard units- measurement units that are the same size no matter who uses them and when or where they are used.

3-dimensional (3-D)- having length, width, and thickness. Solid objects that take up space, such as balls, rocks, boxes, and books, are 3-dimensional.

Trade-first method- one method for solving subtraction problems

Trapezoid- a 4-sided polygon that has exactly one pair of parallel sides.

Turn-around facts- numbers can be added or multiplied in either order. 3+5=8 and 5+3=8 are turn-around addition facts. 4x5=20 and 5x5=20 are turn-around multiplication facts. There are no turn-around facts for subtraction and division if the numbers are different.

2-dimensional (2-D)- Having length and width but not thickness. Flat shapes that take up area, but not space, are 2-dimensional. For example, rectangles, triangles, circles, and other shapes drawn on paper or a flat surface are 2-dimensional.

U.S. customary system- a measurement system that is used most commonly in the United States. Units for length include inch, foot, yard, and mile; units for weight include ounce and pound.

Vertex (plural: vertices) – a point where the sides of an angle, the sides of a polygon, or the edges of a polyhedron meet; any corner of a solid.

Volume- the amount of space inside a 3-dimensional object. Volume is measured in cubic units, such as cubic centimeters or cubic inches. The volume or capacity of a container is a measure of how much the container will hold. Capacity is measured in units such as gallons or liters.

“What’s My Rule?” problem- In Everyday Mathematics, a problem in which two of the three parts of a function (input, output, and rule) are known and the third is to be found out.