National Center for Educational Statistics Graphing Website:
Data can be displayed in many ways, for example:  
  1. Line Graphs
  2. Pie Charts
  3. Bar Graphs
Examples of these data displays are shown below.
Line Graphs
A line graph is a way to summarize how two pieces of information are related and how they vary
depending on one another. The numbers along a side of the line graph are called the scale. The
horizontal scale is called the x axis and the vertical is called the y axis.
Line Graph Example:

The graph above shows how John's weight varied from the beginning of 1991 to the beginning of 1995.
The weight scale runs vertically, while the time scale is on the horizontal axis. Following the gridlines up
from the beginning of the years, we see that John's weight was 68 kg in 1991, 70 kg in 1992, 74 kg in
1993, 74 kg in 1994, and 73 kg in 1995. Examining the graph also tells us that John's weight increased
during 1991 and 1995, stayed the same during 1991, and fell during 1994.
Pie Charts
A pie chart is a circle graph divided into pieces, each displaying the size of some related piece of information.
Pie charts are used to display the sizes of parts that make up some whole (percentages or fractions of one).

Pie Chart Example: Sausage and Mushroom Pizza

Note that the sum of the decimal sizes of each slice is equal to 1 (the "whole" pizza").
0.50 + 0.125 + 0.05 + 0.075 + 0.25 = 1.0
Bar Graphs
Bar graphs consist of an axis and a series of labeled horizontal or vertical bars that show different values for
each bar or category. The numbers along a side of the bar graph are called the scale. The scale numbers can
be on the y axis (vertical) or the x axis (horizontal) depending on how the data are presented.  The two
examples below show horizontal bars and the scales are on the x axis in each graph.

Bar Graph Example 1:
The bar chart below shows the weight in kilograms of some fruit sold one day by a local market. We can see
that 52 kg of apples were sold, 40 kg of oranges were sold, and 8 kg of star fruit were sold.

Bar Graph Example 2:

A double bar graph is similar to a regular bar graph, but gives 2 pieces of information for each item on the
vertical axis, rather than just 1. The bar chart below shows the weight in kilograms of some fruit sold on two
different days by a local market. This lets us compare the sales of each fruit over a 2 day period, not just the
sales of one fruit compared to another. We can see that the sales of star fruit and apples stayed most nearly
the same. The sales of oranges increased from day 1 to day 2 by 10 kilograms. The same amount of apples
and oranges was sold on the second day.

The pie chart shows the
ingredients used to make a
sausage and mushroom

The fraction of each
ingredient by weight is
shown in the pie chart.  
  • Half of the pizza's
    weight comes from
    the crust.
  • The mushrooms
    make up the smallest
    amount of the pizza by
    weight, since the slice
    corresponding to the
    mushrooms is
The points which are
used to connect
together to form a line
include the year and
the weight for that
year.  For eample:  in
1991 John weighed
68 kilograms (kg).  
The x value is 1991
and the y value is 68
kg.  These two values
can be written as
(1991,68).  It is where
the 1991 value is 68
kg that a point is
placed.  Connecting
all the point together
results in the line
Graphing Help                                     M. Elizabeth
Grant High School
steelhead and Salmon