1. 3. Sometimes, the variable that is deliberately changed (the manipulated variable) can have many different values, like the many lengths of the pendulums in Activity 2. Sometimes, the manipulated variable has only a few values, like the three sizes of magnets (small, medium, large) in Activity 3. In this experiment, how many different types of Earth’s materials are being used? What are the values of the manipulated variable?
2. 4. What method is used to measure the responding variable?
3. 5. What other variables are kept the same (controlled) during the experiment?Now you are ready to make a decision about whether the experiment is a fair test, and if its design is good. You only have one more question to answer.
4. 6. Is there any other variable (besides the manipulated and responding variables) that changes in the experiment? If the answer is “no,” then the experiment is a fair test. If the answer is “yes,” then the experiment is not a fair test.
5. 7. Is the experiment a fair test? Explain your answer.Use the questions above to analyze the following two experiment designs. Decide whether each experiment is or is not a fair test.

Imagine you are asked to help an elementary student with her science project. The student wants to find out if hot or cold water freezes faster.

Experiment 2: If you start with two different temperatures of water (one hot and one cold), how does the time it takes for the water to freeze change?

The student started the experiment at home. She filled two ice trays full of water. One ice tray was plastic and was filled with hot water. The other ice tray was metal and was filled with cold water. Both trays were the same size.

She placed both ice trays in the freezer. She placed one tray on the top shelf and one on the bottom shelf. She then checked the ice trays every 15 minutes to see if the water had frozen. In order to help the student, you first have to decide if her experiment is a fair test.

1. Answer the questions about the freezing-water experiment.