Why do we use graphs? It’s an organized way to express data Allows for easy interpretation of the data
What are the parts of a graph? Independent variable: –Goes on “x” (horizontal) axis –Controlled by the experimenter Dependent variable: –Goes on “y” (vertical) axis –Result of applying the independent variable Let’s do a practice problem!
Determining variables The table shows data collected on the pH of a lake in the Adirondacks over 16 years. Based on the table, what is the independent variable and what is the dependent variable? –ANS: IND = year DEP = pH level DEP = pH level
Setting up your graph Now we know the variables, so we know where to plot them –On X axis (independent) Year –On Y axis (dependent) pH pH Year
Plotting your data You are now able to plot your data Year pH
Interpreting your graph What is the trend in pH of this lake over 16 years? –pH decreases –pH becomes more acidic What environmental condition(s) could’ve caused this trend? –Burning fossil fuels –More factories in the area –More industrialized –More cars