This document defines various 6th grade math vocabulary terms in 3 sentences or less per term. There are over 50 terms defined ranging from acute angle, area, capacity, to vertical, vertex, and more. The definitions provide clear and concise explanations of common math terms students need to understand at the 6th grade level.

1. 6th Grade
Math Vocabulary

2. Acute Angle
• An angle whose measure is between 0° and
90°.

3. Area
• The amount of
surface inside
a closed area.

4. Capacity
• The maximum amount or
number that can be received
or contained; cubic contents;
volume:
– The bleachers are filled to
capacity.
– The gasoline tank has a
capacity of 20 gallons.

5. Common Denominator
• A common multiple of the denominators of
two or more fractions.

6. Complementary Angle
• Two Angles are Complementary if they add up
to 90 degrees (a Right Angle).

7. Composite Number
• A Composite Number can be divided evenly by numbers
other than 1 or itself.
– Example: 9 can be divided evenly by 1, 3 and 9.
– Example: 10 can be divided evenly by 1, 2, 5, and 10.
– All even numbers except 2 are composite numbers.

8. Congruent
• Exactly equal in size and shape.
• Congruent sides or segments have the exact same length.
• Congruent angles have the exact same measure.
These triangles are congruent.
Corresponding sides and angles
are congruent.

9. Diameter
• any straight line segment that passes through the
center of a circle and whose endpoints are on the
circle.

10. Difference
• the answer to a subtraction problem.
The difference between
9 and 2 is 7.

11. Exponents
• A small raised number used in exponential notation
to tell how many times a base is used as a factor.

12. Factors
• Whenever 2 or more numbers are multiplied to give
a product, each of the numbers multiplied is called a
factor.

13. Graph

14. Horizontal
• parallel to level ground; flat or level.
The pink line is horizontal.

15. Integers
• All positive and negative numbers as well as zero.

16. Interior Angles
• an angle inside a shape.

17. Isosceles Triangle
• A triangle with at least two side equal in
length.

18. Lowest Terms
• A fraction that cannot be reduced.
• Also known as “simplest form”.

19. Mean
• the average of the numbers.
Example 1: What is the Mean of these numbers?
6, 11, 7
•Add the numbers: 6 + 11 + 7 = 24
•Divide by how many numbers (there are 3 numbers): 24 / 3 = 8
The Mean is 8

20. Median
• The middle number in a set of numbers when the
numbers are listed in order from smallest to largest.
To find the Median, place the numbers you are given in value order and find the middle
number.
Example:
Find the Median of {12, 3 and 5}
Put them in order: 3, 5, 12
The middle number is 5, so the median is 5.
Example:
There are fifteen numbers. Our middle number will be the eighth number:
3, 5, 7, 12, 13, 14, 21, 23, 23, 23, 23, 29, 39, 40, 56
The median value of this set of numbers is 23.

21. Metric Units

22. Mode
• The number that occurs most often in a set of
numbers.
To find the mode, or modal value, first put the numbers in order,
then count how many of each number.
Example:
3, 7, 5, 13, 20, 23, 39, 23, 40, 23, 14, 12, 56, 23, 29
In order these numbers are:
3, 5, 7, 12, 13, 14, 20, 23, 23, 23, 23, 29, 39, 40, 56
This makes it easy to see which numbers appear most often.
In this case the mode is 23.

23. Multiples

24. Obtuse Angle
• An angle that is more than 90°.

25. Ordered Pair

26. Parallel
• Lines are parallel if they are always the same distance
apart (called "equidistant"), and will never meet.

27. Percent--%
• Per hundred or out of a hundred.
50% means 50 per 100 And 25% means 25 per 100
(25% of this box is green) (25% of this box is green)

28. Perimeter
• The distance around the outside of a two-dimensional
shape.
The out-of bounds line
forms the perimeter of a
basketball court.

29. Perpendicular Lines
• Lines that meet to form a right angle.

30. Polygon
• A shape that is made up of 3 or more straight line
segments joined end to end to make one closed path.

31. Prime Number
• A Prime Number can be divided evenly only by 1 or
itself.
– 2 is the only even number that is Prime.
Yellow indicates Prime Numbers

32. Product
• The answer of a multiplication problem.
2 x 6 = 12
The product of 2 times 6 is 12.

33. Quotient
• The answer to a division problem.

34. Radius
• The distance from the center to the edge of a circle

35. Ratio
• A ratio shows the relative sizes of two or more
values.
There are 3 blue squares to 1 yellow square.

36. Reflection

37. Right Angle
• A right angle is an internal angle which is
equal to 90°

38. Scalene Triangles
• A triangle with sides of three different lengths.

39. Simplify
• To express a fraction in simpler form.
Lowest term or
simplest form

40. Slide

41. Standard Form

42. Sum
• The answer to an addition problem.
12 + 13 = 25
The sum of 12 and13 is 25.

43. Supplementary Angles
• Two Angles are Supplementary if they add up to 180
degrees.

44. Vertex
• A point where two or more straight lines meet.
• The plural of vertex is "vertices".

45. Vertical
• being in a position or direction perpendicular to
the plane of the horizon; upright; up and down.

46. Vertical Angle
• the angles opposite each other when two
lines cross