Coordinate graphing sounds complex but it is really just a visual
way of showing the relationships between numbers. These relationships
are shown on what is called a coordinate grid which as two perpendiculars
lines, or axes, labeled like number lines. The horizontal axis is
called the x-axis and the vertical is called the y-axis and the intersect
is called the origin. The numbers on a coordinate grid are used to
locate points. Each point is identified by an ordered pair of numbers.
The number on the x-axis is called an x-coordinate and a number on
the y-axis is called the y-coordinate. Ordered pairs are written in
parentheses (x-coordinate, y-coordinate). The origin is located at
(0,0).
The order in which you write x- and y-coordinates in an ordered pair
is very important. The x-coordinate always comes first, followed by
the y-coordinate. Now before you attempt to conquer coordinate graphs
there are a few things that you need to know. You have to be able
to differentiate between negative and positive numbers and be able
to locate points on a number line. It is wise to start off with a
basic number line and modeling where positive and negative numbers
are on one axis before beginning with the coordinate plane. Stay in
tune with all of the math terms or technical terms such as quadrants,
axis, and coordinate plane, coordinate points, etc., then they won't
seem so intimidating. Coordinate planes are used a lot throughout
math and math related subjects (such as physics). They are most useful
when you need to graph an equation. The graphing points on a coordinate
plane are usually covered in the typical pre-algebra course.
So what makes coordinate graphing different from the rest? Pictographs,
circle graphs, double bar graphs, comparison line graphs, these are
all part of the algebraic graphing options that are available but
it can be confusing and how is one to know which graph to use and
when to use it. But wait-there are more choices, line graphs, pie
charts, bar graphs, area graphs, and x-y plots now what? Line graphs
are used to track changes over short and long periods of time. When
smaller changes exist, line graphs are better to use than bar graphs.
Line graphs can also be used to compare changes over the same period
of time for more than one group. Pie charts are best to use when you
are trying to compare parts of a whole. They do not show changes over
time. Bar graphs are used to compare things between different groups
or to track changes over time. However, when trying to measure change
over time, bar graphs are best when the changes are larger. Area graphs
are very similar to line graphs. They can be used to track changes
over time for one or more groups. Area graphs are good to use when
you are tracking the changes in two or more related groups that make
up one whole category (for example public and private groups. X-Y
plots are used to determine relationships between the two different
things. The x-axis is used to measure one event (or variable) and
the y-axis is used to measure the other. If both variables increase
at the same time, they have a positive relationship. If one variable
decreases while the other increases, they have a negative relationship.
Sometimes the variables don't follow any pattern and have no relationship.
There are numerous graphs that can be used depending on what it is
that you are trying to analyze or show. Decide which type of information
that you are trying to display and then it should be much easier to
know which graph to use and why.