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 CR006003: An experiment in which the amount of bleach and the size of a stain on a shirt were held constant, and the type of bleach varied, could tell you which of two bleaches was better at removing stains.
A student wants to find out if Bleach X or Bleach Y is better at removing stains.
He plans to use two white shirts, stain each of them with mustard, and then wash each of them using bleach. He can change the size of the stain on the shirt and the amount of bleach he adds to the water.
Which two tests should the student set up, the tests in A, B, C, or D?
- Distribution of Responses
- Students Responding Correctly
| Group | Correct | Total | Percent |
|---|---|---|---|
| Overall | 1840 | 2543 | 72% |
| Grades | |||
| 6–8 | 914 | 1366 | 67% |
| 9–12 | 916 | 1164 | 79% |
| Gender | |||
| Male | 882 | 1254 | 70% |
| Female | 945 | 1268 | 75% |
| Primary Language | |||
| English | 1621 | 2187 | 74% |
| Other | 192 | 318 | 60% |