1. Graphing

2. Variables
Independent Variable: A measurement in the lab that you have either chosen specifically or have no control over. In chemistry this is usually time or temperature.
Dependant Variable: A measurement in the lab that changes when the independent variable changes.

3. Line graphs are used when data is taken over time.

4. Line Graphs
You must …
Determine your independent variable and label the x axis (horizontal).
Determine your dependent variable and label the y axis (vertical).
Make sure you use even intervals to number your graph.
Circle and connect the points.
Title your graph: Independent variable versus dependent variable.
Use rulers and pencil.

5. Interpolation
Interpolation means reading between points. For example, the graph below does not show the exact point for 300mL but we can estimate the mass to be 120g.

6. Extrapolation
Extrapolation means reading past the graph. For example, the graph below does not show anything higher than 800mL but we can estimate at 1000mL the mass may be 500g.

7. Direct versus Indirect
Direct graphs show both the x and y variables increasing at a steady rate.

8. Direct versus Indirect
Indirect graphs show one variable increasing while the other is decreasing at a steady rate.

9. Best Fit Line
When point are given that resemble a line, you may be asked to make a “best fit line” which means use a ruler to find the estimated linear correlation: