1. Types of Graphs
And when to use them!

2. Bar Graph This type of graph represents:
Frequency of occurrence (how often…?)
- ex. The average # of times different species of birds visit their nests in a month.
Comparison of magnitude (how much…? How strongly…?)
- the average amount of money spent by the government on different departments

3. Example: How long…?

4. Histogram This type of graph represents a distribution of results
It measures a continuous variable (height of students, Mitch’s savings)
It measures one thing and how this one this is distributed

5. Example: Mitch’s Savings distributed over 7 weeks

6. Example: The number of students distributed over different height ranges

7. Line Graphs
These types of graphs represent a trend over time. They are not appropriate for use when you are working with TWO variables (dependant and independent)

8. Example: How many dolphins seen per year (time)

9. Example: Trey’s height as he ages (time)

10. Scatter Diagram This type of graph is used to compare pairs of values
You could use this graph to measure how a dependant and an independent variable change with respect to each other
Probably a good graph for your science fair project!

11. Example: Temperature (independent variable) vs
Example: Temperature (independent variable) vs. Number of Ice Creams Sold (dependant variable)

12. Now Let’s Try An Example of a Science Fair Project Together

13. Example: Height of Tomato Plant (dependent variable) vs
Example: Height of Tomato Plant (dependent variable) vs. Amount of Fertilizer Added (independent variable)
Step One: Collect and Organize Data
Fertilizer (mL)
Plant Height after 6 weeks (cm) 6 12 10 14 16 18 15 20
100 23

14. STEP 2… Step Two: Represent your data in a chart
(You can do this by hand or using Excel)
Draw in a line of best fit where appropriate
X values- independent
Y-values- dependent

15. STEP 3… Step Three: Make sure that your graph is completely labeled
There must be a TITLE
Each AXIS should be labeled with units
There should be a FIGURE CAPTION explaining what the graph is showing

16. Figure Caption Example
Figure 1: Changes in height of tomato plant compared to how much fertilizer was added to soil. The height of the plants were measured after a 6 week period
Start by numbering your figure.
Then use a caption to convey the information (not a full sentence). You may add any additional information using full sentences.
Don’t add excess information, only describe what is being shown in the figure. Don’t give analysis or conclusions

17. Amount of fertilizer (mL)
Fig. 1:Tomato Plant Height vs. Amount of fertilizer Y
Height of plant (cm) X
Amount of fertilizer (mL)
Figure 1: Changes in height of tomato plant compared to how much fertilizer was added to soil. The height of the plants were measured after a 6 week period