Original Project
Control of Variables
If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be cl…
Item CR024005: An experiment in which variable X is allowed to vary and variables Y and Z are held constant could tell you if variable X has an effect on the result of the experiment.
A student thinks that there are three variables (X, Y and Z) that may affect the result of her experiment.
What should the student do to find the effect of variable X on the result of the experiment?
- Change variable X and keep variables Y and Z the same.
- Change variables Y and Z at the same time and keep variable X the same.
- Change variable X and Y at the same time and keep variable Z the same.
- Change variables X, Y, and Z at the same time.
- Distribution of Responses
- Students Responding Correctly
| Group | Correct | Total | Percent |
|---|---|---|---|
| Overall | 1205 | 2371 | 51% |
| Grades | |||
| 6–8 | 567 | 1284 | 44% |
| 9–12 | 636 | 1078 | 59% |
| Gender | |||
| Male | 622 | 1164 | 53% |
| Female | 570 | 1170 | 49% |
| Primary Language | |||
| English | 1088 | 2084 | 52% |
| Other | 90 | 227 | 40% |