1. Graphing in Science

2. Why Graph in Science? Graphs are pictures of data.
It is important to choose the type of graph that best illustrates your data.
We will have 3 types of graph this year:
Bar
Line
Pie

3. Bar Graph
Best used for comparing groups quickly and easily.

4. Line Graph
Best used for comparing how one variable effects another variable.

5. Pie Graph
Best used for showing how something is divided into smaller categories.

6. What type of graph would we use?
Rabbit Dietary Preferences
Food
Percent Preferring that Food
Skippy’s Rabbit Chow 32
Homemade Rabbit Food 13
Happy Rabbit 10
Joe’s special food for rabbits 44
Premium Rabbit Nutrition Diet 1
Type?
Why?

7. What type of graph would we use?
Monthly Science Grades
Month
Grade in Science Class
September 98
October 94
November 88
December 78
January 82
February 83
March 86
April 81
May 97
Type?
Why?

8. What type of graph would we use?
pH of Solutions
Test Tube Number pH 1
6.7 2
7.1 3
7.4 4 5
7.0
Type?
Why?

9. Components of a Good Graph
Graphs require the correct ingredients, or components to make them neat and easy to understand.

10. Setting Them Up
For bar and line graphs, first set up your x-axis and y-axis using a ruler.
The x-axis is horizontal
The y-axis is vertical
The dependent variable is the data collected during the experiment. It responds to the change in the independent variable. This is placed on the y-axis.
The thing that is controlled by the experimenter, the independent variable, is placed on the x-axis.

11. Setting Them Up Next, choose a scale for each of the axes.
Select regularly spaced intervals that include all of your data.
Always label your axis and include appropriate units where they apply.
Include a key when necessary to clarify your data.

12. Setting Them Up Finally, give your graph a title.
A title tells the reader what he or she is looking at.
A good title should explain the relationship between variables.

13. Pie Graphs Pie graphs are shaped like a circle.
The size of each slice is determined by the percent it will represent.

14. Identifying Relationships
Linear: One variable changes directly proportional to the other. The line is straight and has a slope that does not equal zero. This line should fit the equation y=mx + b.

15. Identifying Relationships
Inverse: curved graph. If you double variable 1, variable 2 should decrease by ½, etc.

16. Identifying Relationships
Square: curved graph. If you double variable 1, variable 2 should increase by a factor of 4. This should fit the formula y=x2

17. Identifying Relationships
Square Root: curved graph. If you quadruple variable 1, variable 2 should decrease by a factor of 2, etc. These graphs should fit the formula y=x or x½