1. Graphing

2. Types of Graphs
We use different types of graphs for different purposes
Pie charts are used to show percentages
Bar graphs are used to compare changes over time or to compare items
Line graphs are used to look for trends in the change in the dependent variable as the independent is changed

3. Line Graphs
The independent variable (the one being changed) is the x-axis and the dependent variable is the y-axis
Label each axis with its value and type of measurement
Your graph should have each axis start at zero, but you can use a symbol to show that you are skipping values

4. Line Graphs (cont)
You can divide the range of values by the number of boxes to help you pick a scale
Place a dot where the values for both the x-axis and y-axis meet
Connect the dots with a line

5. Line Graphs (cont) Graph the following data points
Elevation (m)
Temperature (°C)
100
19.5
200
18.7
300 18
400
17.5
500
16.8
600 16
Graph the following data points
The independent variable is elevation and the temperature is the dependent variable

6. Interpreting Line Graphs
If a slope is close to being linear (straight line) there is a direct relationship between the variables.
If the line goes up from left to right it means as the independent variable increases the dependent variable increases with it
If the line sinks as it goes to the right it means as the independent variable increases the dependent variable decreases

7. Interpreting Line Graphs (cont)
Proportional (increase together)
Inversely proportional (independent increases, but the dependent decreases)

8. Interpreting Line Graphs (cont)
Time (hours)
Distance (Km) 1 10 2 20 3 30 4 40
Graph the following data points
The independent variable is time and the distance is the dependent variable
What is the relationship between time and distance?
Proportional

9. Interpreting Line Graphs (cont)
Time (sec)
Position (m) 60 2 50 4 40 6 30 8 20 10
Graph the following data points
The dependent variable is position and the time is the independent variable
What is the relationship between position and distance?
Inversely proportional