Graph: a picture of information from a data table;
shows the relationship between variables.
3 types used by scientists:
1. Bar graph
2. Line graph
3. Circle graph
Line Graphs are used to display data to show how
one variable (the responding variable) changes in
response to another the variable manipulated
variable).
How to draw a line graph:
1. Draw the axes. The horizontal axis (x-axis) is
at the bottom of the graph and runs left to
right. The (y-axis) runs up and down.
2. Label the axes. The horizontal axis with the
name of the manipulated variable and the
vertical axis with the name of the responding
variable.
3. Create a scale. Create a scale by marking off
equally spaced intervals that cover the range
of values. The point where the two axes cross
is called the origin. (0,0) A coordinate is a
pair of numbers used to determine the
position of a point on a graph.
4. Plot the data. Plot a point for each and every
piece of data. Plot a point where these two
lines cross or intersect. The point showing the
location of that intersection is called the data
point.
5. Draw a line of best fit. This is a smooth line
that reflects the general pattern of the graph.
Remember a line graph in which the data
points yield a straight line is called a linear
graph.
6. Add a title that indicates the variables or
relationship.
7. Slope is the steepness of a graph. The slope of
a graph line tells you how much y changes for
every change in x.
1 (x,y)
2(x,y)
Slope = rise = y2 – y1
run
x2 – x1
example: (20,10) (50,25)
25 – 10 = 15 = ½ or .5
50 – 20
example:
30
(15,10) (25,50)
50 – 10 = 40 = 4/1
25 – 15
10
Chart or Table: a set of data arranged in rows and
columns.
Favorite Student After School Activity
Activity
Visit with friends
Talk on Phone
Play Sports
Earn Money
Use Computers
Number of students
175
168
120
120
65
Bar Graph: A graph that uses bars of different
lengths to show relationships.
Horizontal or vertical.
Type of Pet