Miss Castellana's Graphing Hints

• Graphs may be generated on the computer. If they are constructed by hand use graph paper. If more than one data set is represented, use colored pencils.
• Label your graph with an accurate, descriptive title.
• Always record the independent variable on the X-(horizontal) axis. The dependent variable should be on the Y-(vertical) axis. Be sure to specify the units.
• Space intervals evenly along each axis. Plot data points only at coordinates where data were collected.
• Set the maximum values on both axes slightly above the maximum values of the data. The data should extend over most of the graphs area.
• Independent vs. Dependent Variables: How can you tell? Take a look carefully at your experiment. In any good, controlled experiment you are changing something to see what influence it might have during your experiment. What precisely are you changing? This factor is your independent variable. It is deliberately changed during the course of your experiment. The dependent variable changes in response to the independent variable. It responds to the independent variable.

                  Example: Miss Castellana wanted to study the influence of temperature on plant growth. She set up 5 aquariums. Each aquarium contained three plants. Heat lamps were assembled facing into the tanks. Miss Castellana adjusted the temperature in each tank by adjusting the intensity of the heat lamps. The growth of each plant was measured and recorded everyday for two weeks.

  What is the independent variable in her experiment? (Hint: What did Miss C deliberately change in the experiment?) The temperature!

  What is the dependent variable? (Hint: What factor changed as a result of the independent variable?) What happened as a result of Miss C changing the temperature? The plants grew different amounts. This is your dependent variable - GROWTH!