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Mathematics Glossary - Middle Years
Maxine Stinka, Saskatchewan Education, Curriculum and Instruction

Note: The definitions included here are those that are used in the Saskatchewan Education document "Mathematics 6-9: A Curriculum Guide for the Middle Level".

Various mathematics dictionaries may have different definitions. These definitions are designed to be meaningful to middle level mathematics teachers.

Select the first letter of the term that you wish to look for.
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negative integer exponent

negative rational number


  • a plane figure obtained by opening and flattening a 3-D object.


obtuse angle

  • an angle whose measure is between 90o and 180o.

obtuse triangle

  • a triangle with one obtuse angle.


  • the ratio of the probability that an event will occur compared with the probability of its not occurring.

open expression

opposites (additive inverses)

  • two numbers whose sum is 0.

  ordered pair

  • a pair of numbers for which the order is important. E.g. a pair of numbers that gives the location of a point in a plane such as (3,1). The order of the numbers in the pair is important because the point (1,3) is not the same as the point (3,1).


  • the second element in a coordinate pair. When graphed in the coordinate plane, it is the distance from the x-axis. Frequently called the y coordinate.


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