# Third Grade Math Essential Facts by zhangyun

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• pg 1
Number and Operations

1.    A whole number (0, 1, 2, 3…) is a counting number.
2.    Less than (<) means smaller than something to which it is being compared.
3.    Equal to (=) means the same as something to which it is being compared.
4.    Greater than (>) means larger than something to which it is being compared.
5.    An algorithm is a set of rules you follow to solve a problem.
6.    A fraction is part of a whole (e.g., 1/3).
7.    Repeated addition is the same as multiplication.
8.    Repeated subtraction is the same as division.
9.    Odd numbers are every other number starting with 1 (e.g., 1, 3, 5, 7, etc.)
10.   Even numbers are every other number starting with 2 (e.g., 2, 4, 6, 8, etc.)
11.   A multiple is more than one item.
12.   The place value of a number is determined by its position in the number.

Algebra

13.   The inverse of a problem is the opposite or reverse.
14.   When a number is increasing, it is going up in value.

Geometry

15.   The middle point of a circle is the center.
16.   A diameter is the line from one end of the circle across the center to the other end.
17.   The radius of a circle is half the diameter.
18.   The outer boundary of a circle is the circumference.
19.   A closed plane with three or more sides is a polygon.
20.   A triangle is a polygon with three sides.
21.   A quadrilateral is a polygon with four sides.
22.   A pentagon is a polygon with five sides.
23.   A hexagon is a polygon with six sides.
24.   An octagon is a polygon with eight sides.
25.   A line has a beginning and an end.
26.   A line segment is a portion of a line.
27.   Two lines that extend in the same direction and are of equal distance apart but never touch are
parallel lines.
28.   Perpendicular lines are lines that are straight up and down.
29.   Intersecting means crossing over.
30.   An angle is made by two lines coming out from a specific point.
31.   A right angle is 90 degrees.
32.   An acute angle is less than 90 degrees.
33.   An obtuse angle is greater than 90 degrees.
34.   A scalene triangle is a triangle with three unequal sides.
35.   An isosceles triangle has two equal sides and one side that is more or less than the other
two.
36.   An equilateral triangle has three equal sides.
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Greenville Chamber Foundation
37.   One line coming out from a point is a ray.
38.   A transformation is the movement of an object through sliding, flipping or turning.
39.   A slide transformation is the moving of an object’s location to the left or right.
40.   A flip is when you change an object to look like its mirror image.
41.   A turn is when you change an object a certain degree.

Measurement

42.   A coin is a small flat circular object that is used as money (e.g., a quarter).
43.   A meter is a unit of length.
44.   An inch is unit of length. There are 12 inches in one foot.
45.   60 seconds = 1 minute
46.   36 inches = 1 yard
47.   Mass is measured in grams.
48.   The amount of space in an object is called volume.
49.   An ounce is a unit of weight.
50.   8 liquid ounces = 1 cup
51.   2 cups = 1 pint
52.   2 pints = 1 quart
53.   4 quarts = 1 gallon
54.   16 ounces = 1 pound
55.   A pint and a liter are used to measure liquid.
56.   A yard is a unit of measure equal to three feet.
57.   A kilometer is a unit of length equal to 1,000 meters.
58.   A perimeter is the border or outer boundary of a two-dimensional figure.
59.   An analog clock has hands that point to the hour and the minute.
60.   A digital clock shows the numbers in digits.

Data Analysis and Probability

61.   The range is the difference from the largest number to the smallest number in a given set.
62.   A bar graph is a graph that uses parallel bars to illustrate the data.
63.   A pictograph is a graph that uses pictures to represent data.
64.   A dot graph is used to keep track of how often something occurs.
65.   Probability is how likely something is to occur. Probability can be likely, unlikely, certain or
impossible.
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