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 CR019002: A controlled experiment involving the floating of clay boats, in which the shape of the boats varies and the weight of the boats stays the same, can tell you if shape affects the floating of the boats.
A group of students uses clay to make boats of different shapes. All the boats they make have the same weight. The students add four tablespoons of salt in the water in a tank and mix the water. They place the boats in the tank and see if the boats float or sink.
What can the students find out from doing just this experiment?
- If shape affects whether the boats float or sink.
- If weight affects whether the boats float or sink.
- If weight and the amount of salt in the water affect whether the boats float or sink.
- If shape, weight, and the amount of salt in the water affect whether the boats float or sink.
- Distribution of Responses
- Students Responding Correctly
| Group | Correct | Total | Percent |
|---|---|---|---|
| Overall | 1446 | 2564 | 56% |
| Grades | |||
| 6–8 | 693 | 1386 | 50% |
| 9–12 | 744 | 1165 | 64% |
| Gender | |||
| Male | 693 | 1262 | 55% |
| Female | 739 | 1280 | 58% |
| Primary Language | |||
| English | 1295 | 2208 | 59% |
| Other | 127 | 317 | 40% |