Third Grade Everyday Math Vocabulary 
Please note that the words for each unit are listed by the order in which they are covered, not alphabetically.
Unit One: Routines, Review, & Assessment unit –a symbol that tells what a number means like feet, degrees, minutes, etc. number grid –a table that lists numbers in order data base a collection or set of information template a stencil used for drawing geometric shapes frames and arrows a diagram used to show a number pattern or sequence tally chart –a chart that uses tally marks to show how many times each value appears in a set of data bar graph –a graph that uses bars to represent numbers in the data name collection box –a place to write equivalent names for the same number estimation –an answer that is close to the exact answer calculate –to figure out an answer using numbers Unit Two: Adding and Subtracting Whole Numbers fact family/ number family related addition and subtraction facts or related multiplication and division facts difference the answer to a subtraction problem fact extension a method of using a math fact to solve a bigger problem like if 5+7=12 then 50+70=120 function machine –an imaginary machine used to change numbers from input to output according to a given rule partsandtotal diagram –a diagram that is used to keep track of the numbers and missing information in problems where two parts are combined to find a total number model –equation showing how a number story is solved change diagram –a diagram used to keep track of numbers and missing information in a number story in which an amount is increased or decreased ballpark estimate –a good rough estimate used when you don’t need an exact answer or to check if an answer makes sense addend –a number that is added in an addition problem sum the answer to an addition problem Unit Three: Linear Measures and Area inch unit of measure representing 1/12 of a foot line segment a strait path between two endpoints centimeter a unit of measure representing 1/100 of a meter millimeter –a unit of measure representing 1/1000 of a meter perimeter –the distance around a shape polygon –a closed figure on a flat surface that is made up of line segments joined endtoend; the line segments of a polygon may not cross area –the amount of surface inside a shape measured in square units square foot –a unit of surface area measuring 1 ft X 1 ft circumference –the distance around a circle (its perimeter) diameter –a line segment that goes through the center of a circle and has endpoints on the circle Unit Four: Multiplication & Division multiplication –the operation of putting together numbers of equal groups array an arrangement of objects in rows and columns factor any of the numbers that are multiplied to find a product; a number that divides another number evenly; 8 is a factor of 24 product the answer to a multiplication problem quotient the answer to a division problem dividend the number to be divided in a division problem divisor the number being divided into the dividend in a division problem remainder the amount left over when things are divided or shared equally square numbers numbers that result from multiplying 2 of the same factors: 2,4,9,16,25,36… Unit Five: Place Value in Whole Numbers & Decimals place value the system for writing numbers in which the value of a digit depends on its place in the number greater than > bigger than, the arrow opens to “eat” the bigger number less than , smaller than, the arrow points at the smaller number pie graph a circular graph that represents amounts as different size pieces of “pie” decimals parts of a whole represented in tenths, hundredths, thousandths, etc.. tenths a decimal representing a part of a whole where ten parts would equal one whole hundredths a decimal representing a part of a whole where 100 parts would equal one whole thousandths a decimal representing a part of a whole where 1000 parts would equal one whole decimeter a unit equal to 10 centimeters or 1/10 of a meter Unit Six: Geometry line segment –a straight path between two endpoints end point –the point at the end of a ray or line segment ray a straight path that has one end point and goes on forever line a straight path that goes on forever in both directions parallel always the same distance apart and never meeting or crossing each other, no matter how far extended intersect –to meet or cross angle a figure that is formed by two rays or two line segments that have the same end point right angle a 90^{o }angle, its sides form a square corner vertex the point where the rays of an angle or the sides of a polygon or the sides of a polyhedron meet equilateral –having sides of equal length quadrangle –a polygon that has 4 sides and 4 angles, the same as a quadrilateral square a rectangle whose sides are all the same length rhombus a parallelogram with all 4 sides the same length parallelogram a foursided polygon that has 2 pairs of parallel sides; the parallel sides are also the same length rectangle –a parallelogram whose corners are all right angles trapezoid a foursided polygon with exactly one pair of parallel sides adjacent sides sides that share a vertex kite a foursided polygon with 2 pairs of equal sides; the equal sides are next to each other; the four sides cannot all have the same length degree a unit of measure for angles; also a unit of measure for temperature symmetry figure with at least one line that can divide the figure into 2 parts look exactly alike but are pointing in different directions; if you fold the figure in half the two halves match exactly congruent figures figures that have the same shape and size polyhedron a geometric solid whose surfaces or faces are all formed by polygons cone a solid that has a circular base and a curved surface that ends at a point called the apex cylinder a solid that as 2 circular bases that are parallel and the same size; the bases are connected by a curved surface sphere a solid with a curved surface that looks like a ball pyramid a solid that has one base that is a polygon; all the other sides (or faces) are triangles that come together at a point called a vertex or apex prism a solid that has a parallel bases that are polygons with the same size and shape; all other faces are parallelograms base a name used for the side of a polygon and a face of a threedimensional figure face a flat surface on the outside of a solid edge a line segment or curve where the edges of a solid meet Unit Seven: Multiplication and Division factor –any of the numbers that are multiplied to find a product product the answer to a multiplication problem square product the number resulting from multiplying a number times that number again 4, 9, 16, 25, 36…. parentheses the way to tell which part of a multistep algorithm should be completed first Unit Eight: Fractions whole one complete number or figure, represented by the number 1 denominator the number below the line in a fraction, representing the number of parts you must have to make one whole numerator the number above the line in a fraction representing the number of parts you have equivalent fractions two or more fractions broken into different size pieces (having different denominators) that represent equal portions of a whole mixed number a number that combines a whole number and a fraction like 1 ½ Unit Nine: Multiplication and Division algorithm a method of solving a problem lattice multiplication a method for solving a multiplication problem using a lattice diagram; positive number a number greater than zero negative number a number less than zero degrees Fahrenheit unit of temperature measurement used in the U.S. customary system degrees Celsius unit of temperature measurement used in the metric system Unit Ten: Measurement and Data volume the amount of space inside a 3d object, usually measured in cubic units cubic centimeter unit of volume measurement; a cube measuring 1 cm X 1 cm X 1 cm weight measurement of how heavy something is capacity the amount a container or scale can hold precision the accuracy to which something can measure mean an 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 umber in a set of data when the numbers are put in order from smallest to largest or largest to smallest mode the number or value that occurs most often in a set of data coordinate the location of a point on a grid, usually given in ordered pairs Unit Eleven: Probability probability a number between 0 and 1 that is used to tell the chance of something happening event something that happens; tossing heads with a coin and rolling 3 with a die are events random draw picking out something blindly without looking or in any way intentionally making a choice chance the possibility that something will occur certain absolutely sure to occur impossible absolutely sure NOT to occur percent an amount out of 100; 100% means all; 50% means half equally likely having the same chance of happening
