Examples:

sample  A subset of a population used to represent the whole population.

scale  The ratio of the distance on a map, globe, or drawing to the actual distance.

scale drawing  An accurate picture of an object in which all parts are drawn to the same scale.  If an actual object measured 33 by 22 yards, a scale drawing of it might measure 33 by 22 millimeters.

scale factor  A number that names “How many times as many” or “What fraction” one quantity is of another quantity.

scale model  A model that represents an object or display in proportions based on a determined scale.

scientific calculator  A calculator which displays very large or very small numbers in scientific notation and has powering, square root, change-of-sign, and reciprocal keys.

scientific notation  A system for representing numbers in which a number is written as the product of a power of 10 and a number that is at least 1 but less than 10.  Scientific notation allows writing big and small numbers with only a few symbols.  For example, 4,000,000 in scientific notation is 4 * 10⁶.  0.00001 in scientific notation is 1 * 10^-5.

section (of land)  A land unit equal to one square mile, 640 acres or 1/36 of a township.

sector  A region bounded by an arc and two radiuses of a circle.  The word wedge is sometimes used instead of sector.

semicircle  See arc.

semiregular tessellation  A tessellation made up of two or more kinds of regular polygons.  In a semiregular tessellation, the angles around any vertex point must be congruent to the angles around any other vertex point.

Sieve of Eratosthenes  A method credited to the mathematician Eratosthenes (about 200 B.C.) for identifying prime numbers.

sighting  A method that artists use to draw a free-hand copy of a figure.

similar figures  Figures that are exactly the same shape but not necessarily the same size.

simplest form  A fraction in which the numerator and denominator have no common factor except 1 and the numerator is less than the denominator.  Also, a mixed number in which the fraction is in simplest form.

simplify an expression  To rewrite an expression by removing parentheses and/or by combining like terms.  For example, 7y + 4 + 5 + 3y can be simplified to 10y + 9 and 3(2y + 5) – y can be simplified to 5y + 15.

simulation  An activity in which an object or event is represented by something else.

size change  A transformation in which the image is similar to the preimage.

size-change factor  A number that tells the amount of enlargement or reduction of an object in a size-change transformation.

slanted cylinder  A cylinder in which the curved surface is not perpendicular to the base.

solution of an open sentence  A value or values of the variable(s) in an open sentence for which the sentence is true.

solution set  The set of all solutions of an equation or inequality.

Southern Hemisphere  The southern half of the Earth, from the equator to the South Pole.

span  See normal span or great span.

special case (of a pattern)  When values replace the words or variables in a pattern.  For example, 6 + 6 = 12 is a special case of the pattern Y + Y = 2Y.  See also pattern.

speed  A rate that compares distance traveled with the time taken to travel that distance.

sphere  The set of all points in space that are a given distance (the radius) from a given point (the center).  A ball is shaped like a sphere, as is Earth.

spreadsheet  A table displayed by a computer program, which is used to perform mathematical operations, evaluate formulas, and relate data quickly.  The name comes from ledger worksheets for financial records.  Such sheets were often taped together and then spread out for examination.

square array  A rectangular array with the same number of rows as columns.  For example, 16 objects will form a square array with 4 objects in each row and 4 objects in each column.

square number  A number that is the product of a whole number and itself; a whole number to the second power.  25 is a square number, because 25 = 5 * 5.  A square number can be represented by a square array.

square of a number  The product of a number multiplied by itself; symbolized by a raised 2.  For example, 3.5² = 3.5 * 3.5 = 12.25.

square root of a number  The square root of a number n is a number which, when multiplied by itself, results in the number n.  For example, 4 is a square root of 16, because 4 * 4 = 16.  The other square root of 16 is –4 because –4 * (-4) = 16.

square unit  A unit used to measure area – usually a square that is 1 inch, 1 centimeter, 1 yard, or other standard unit of length on each side.

standard notation  The most familiar way of representing whole numbers, integers, and decimals by writing digits in specified places; the way numbers are usually written in everyday situations.

stem-and-leaf plot  A display of data in which digits with larger place values are named as stems, and digits with smaller place values are named as leaves.

step graph  A graph that looks like steps.  Particularly useful when the horizontal axis represents time.

straight angle  An angle of 180 degrees; a line with one point identified as the vertex of the angle.

substitute  To replace one thing with another; in a formula, to replace letters with numerical values.  For example, if b = 4.5 and h = 8.5, then these values can be substituted in the formula A = b * h to give A = 4.5 * 8.5.

subtraction  A mathematical operation based on “taking away” or comparing (“How much more?”).  The number being subtracted is called the subtrahend; the number it is subtracted from is called the minuend; the result of subtraction is called the difference.  In 45 – 12 = 33, 45 is the minuend, 12 is the subtrahend, and 33 is the difference.  Addition “undoes” subtraction.  45 – 12 = 33, and 45 = 12 + 33.

subtrahend  See subtraction.

supplementary angles  Two angles whose measures total 180°.

surface  A basic concept of geometry; usually thought of as a continuous set of points, flat or curved, without thickness.  A surface can be bounded (for example, a circle and its interior or the surface of a cylinder) or unbounded (for example, a plane).

surface area  A measure of the surface of a 3-dimensional figure.

survey  A study that collects data from human respondents.  Surveys are used to find out about people’s characteristics, behaviors, interests, and so on.

symmetry  Having the same size and shape across a dividing line or around a point.