Understanding GraphsMrs. BaldessariBiology

The ability to interpret graphs is a necessary skill in science but also finds use in everyday life. In articles or textbooks you are likely to find graphs. Understanding the article’s message depends heavily on being able to interpret different types of graphs.

Three Types of Graphs(and when to use them)

• Pie charts: show relationships of parts to a whole

• Bar graphs: used to compare values• Line graphs: show the relationship between

two variables

Pie Graph Example

Sample questions: Are more deaths caused in Texas by winter storms or lightning?About what percentage of weather deaths are caused by flooding?

Another pie chart…What’s the most common thing I do while waiting for my toast to pop up?

Another pie chart…What’s the most common thing I do while waiting for my toast to pop up?

Another pie graph…

What percent of people ask if I’m left-handed when I write with my left hand?

Bar Graphs(Used for comparisons)

Are more children born with autism in March or May?

Dependent/Independent variables

• Independent (manipulated) variable: The factor you change during an experiment

• Dependent (resulting) variable: What happens as a result of changing the independent variable

Line Graphs

• Remember your “DRY MIX”• The dependent (resulting) variable goes on

the y-axis.• The independent (manipulated) variable goes

on the x-axis.• Example: Does the age of your car depend on

its value, or does its value depend on its age?• So, which is the dependent variable? Which

axis does it go on?

The dependent variable goes on the y-axis.

Another example

• Does the hour of the day in Boston depend on the temperature?

• Or does the temperature in Boston depend on what hour of the day it is?

Dependent variable:Independent variable:

The dependent variable goes on the y-axis.

If time is a variable, it almost always goes on the x-axis.

In what year would it be hardest for a staff member to find a parking place?

During what two periods of time was this person not moving?

Did this person enjoy his shower?