GRAPHING
Reading, Constructing, and Analyzing
Graphs
Make sure your graph “TALKS” to me!!
T-Title
A-Axis (x axis=independent variable
y axis=dependent variable)
L-Label (everything should be labeled)
K-Key (if appropriate)
S-scale (make sure scale of numbers is
appropriate-don’t always have to use
increments of 1)
Bar Graphs
*easily read, used to graph categories of things,
usually have spaces between the bars
**What is this bar graph missing?
Histograms
*similar to bar graphs except the bars
represent a range of values rather than one
single value and the bars touch each other
*intervals should be equal (1-10, 10-20, etc.)
*width of bars should all be the same
Line Graphs
*shows change over time or relationship
between 2 quantities
*do NOT connect dots after plotting points
Draw a “Line of Best Fit” or a “Curve of Best
Fit”
-Use the points to draw the best straight line
you can; have the line pass through as many
points as possible, with approximately the
same number of points on one side of the
line as the other
Analyzing Graphs
Interpolation—finding a value that is actually
on the graph
Extrapolation-finding a value that lies BEYOND
the actual data on the graph
BAR GRAPH PRACTICE
Use the following data to create a bar graph.
REMEMBER: Make sure your graph “TALKS” to me!!
“Plant Growth: Height Vs Time”
Time (days)
Height (cm)
5
3
10
8
15
11
20
13
25
19
30
25
Bar Graph Questions
Interpolation:
What is the independent variable for this
graph?
How tall was the plant after 10 days?
Extrapolation:
How tall do you think the plant will be after
day 40? Explain.
Histogram Practice
Use the data to create a histogram.
REMEMBER: Make sure your graph “TALKS” to me!
DATA ON THE NEXT SLIDE! 
Life Expectancies in the US
Current Age Remaining Years Expected
0-10
72.6
11-20
59.5
21-30
50.1
31-40
40.7
41-50
31.7
51-60
23.2
61-70
15.8
71-80
9.7
81-90
4.5
Histogram Questions
Interpolation: Mrs. Parker is 38 years old.
About how many more years can she expect
to live according to the graph?
Extrapolation: Make a prediction about the
remaining years of life that would be expected
for someone in the current age category of 91100. Justify your answer. (Give specific
information!)
Line Graph Practice
Use the data on the next slide to create a line
graph.
Remember: Make sure your graph “TALKS” to
me!
Do NOT connect the points after plotting them;
Draw a “Line of Best Fit” or a “Curve of Best
Fit”
Time Vs Position of a Miniature
Motorized Car on a Straight Track
Time (minutes)
0
5
10
15
20
25
Position (meters)
0
15
30
45
60
75
Line Graph Questions
Interpolation:
What is the independent variable for this graph?
What is the dependent variable for this graph?
Determine the position of the car after 2.5 minutes.
Extrapolation:
If the experiment was conducted for 35 minutes,
what would be the position of the car?
How many minutes will it take the car to reach the
position of 180 meters?
Scientific Graphs
Most of the time, scientists use line graphs
instead of the bar graphs; therefore, we will
be using line graphs in science.
You are too young for bars, anyway!!! 
FIST OR FIVE??
Show me a fist if there is something we have
covered about graphs that you still don’t
understand.
Give me a five if you are comfortable with bar
graphs, histograms, and line graphs.