1. Identifying variables

2. Identify possible variables in the following situations.
What variables can affect the sprouting of a bean seed?
What variables can affect the number of books sold by a door-to-door salesperson?
What variables can affect the number of fish in a lake?
What variables can affect attendance at a football game?
What variables can affect the taste of a soft drink?
What variables can affect the speed of a runner in a 100-meter dash?

3. THREE KINDS OF VARIABLES
MANIPULATED (INDEPENDENT) VARIABLE
RESPONDING (DEPENDENT) VARIABLE
CONTROLLED VARIABLES

4. MANIPULATED VARIABLE
A factor or condition that is intentionally changed by an investigator in an experiment

5. RESPONDING VARIABLE
A factor or condition that might be affected as a result of that change

6. CONTROLLED VARIABLES
A variable that is not changed in an experiment.

7. For each experiment, specify the manipulated, responding, & controlled variables.
Two groups of students were tested to compare their speed working math problems. Each group was given the same problems. One group used calculators and the other group computed without calculators.

8. For each experiment, specify the manipulated, responding, & controlled variables.
Students of different ages were given the same puzzle to assemble. The puzzle assembly time was measured.

9. For each experiment, specify the manipulated, responding, & controlled variables.
A study was done to find if different tire treads affect the braking distance of a car.

10. For each experiment, specify the manipulated, responding, & controlled variables.
An experiment was performed to determine how the amount of coffee grounds could affect the taste of coffee. The same kind of coffee, the same percolator, the same amount and type of water, the same perking time, and the same electrical source were used.

11. For each experiment, specify the manipulated, responding, & controlled variables.
A study was attempted to find if the length of the string in a string telephone affected the sound clarity.