1. Graphing in Science Class

3. Why do we use graphing? A useful tool in science
Makes data easier to interpret and make conclusions
Visual characteristics of a graph make trends in data easy to see
Helps us to "predict" data that is not measured on the graph.

4. Types of Graphs There are 3 different types of graphs: –Bar graphs
–Pie graphs
–Line graphs
Each type is used in different situations

5. Bar Graphs Used to show relationships between groups
The items being compared do not need to affect each other.
Fast way to show big differences
Easy to read

7. Circle or Pie Graph
Used to show how a part of something relates to the whole
Used to show percentages effectively

9. Line Graphs Used to show change over time.
Makes it clear to see trends by the rises and falls of the line graph

11. Graphing Steps Decide what type of graph to use Identify the variables
Determine the range
Determine the scale
Number and label each axis
Plot the points
Draw the graph
Give your graph a title

12. Choosing the Right Graph
Bar graph if you are not looking for trends over time and the categories are not parts of a whole
Pie chart if you need to compare different parts of a whole, time is not a factor and there are not too many categories
Line graph if you need to see how a quantity changes over time

13. Identify the Variables
Independent Variable
Experimenter manipulated (the thing you changed)
x axis (horizontal)
Dependent Variable
Depends on the independent variable (how did the independent variable change it?)
y axis (vertical)

14. Determine Range and Scale
Subtract lowest value from the highest value - this is your range
Create a scale that best fits your data - spread out your graph as much as possible to make your graph more readable

15. Number and Label Each Axis
Number the axes keeping in mind your range
Label each axis so that anyone reading your graph can understand what the graph means
Include units of measure

16. Plotting Plot each data value on the graph with a dot.
You can put the data number by the dot if it does not clutter your graph.

17. Drawing
In some cases, you will connect the data points with a straight line
A “Best Fit Line” is a curved or straight line that best fits the data points.
Most graphs of experimental data are drawn as Best Fit Lines
Allows us to Interpolate
Allows us to Extrapolate

18. Interpolation
Interpolate: predicting data between two measured points on the graph.

19. Extrapolation
Extrapolate: extending the graph, along the same slope, above or below measured data.

20. Title Your title should clearly tell what the graph is about
If your graph has more than one set of data, provide a "key" to identify the different lines