Independent and Dependent Variables Scenarios Worksheet

Problem Overview:

The task requires identifying the independent variable and the dependent variable for each scenario provided. The independent variable is the factor that is manipulated or changed by the experimenter, while the dependent variable is the outcome or response that is measured as a result of the manipulation.

Solution:

#### Scenario 3:
Description: One grape is placed in tap water and another grape is placed in salt water. The change in their mass is measured after a day.

- Independent Variable: Salt Water
- Explanation: The type of water (tap water vs. salt water) is the factor being manipulated by the experimenter. This is what changes between the two grapes.

- Dependent Variable: Mass
- Explanation: The mass of the grapes is the outcome being measured. It is expected to change based on the type of water the grapes are placed in.

#### Complete Table with All Scenarios:

| Scenario | Independent Variable | Dependent Variable |
|--------------------------------------------------------------------------|--------------------------------|------------------------------|
| 1. A cow is given a growth hormone and then compared to another cow that was not given a growth hormone. Both cows were weighed at 2 years. | Growth hormone | Weight/mass |
| 2. Mosquito repellent is sprayed on one arm and the other arm is not sprayed. The number of mosquito bites is counted after 2 hours. | Mosquito repellent | Number of mosquito bites |
| 3. One grape is placed in tap water and another grape is placed in salt water. The change in their mass is measured after a day. | Salt Water | Mass |
| 4. Two different cars are traveling at 60 mph. At a certain point, both cars slam on the brakes. The distance it takes for each car to stop is then measured. | Slam on the brakes | Distance Measurement |
| 5. Pillbugs are placed in a container where they have a choice of a wet or a dry environment. Researchers record how much time was spent on each side. | Container | Time |
| 6. A stapler is used to staple 100 papers; it jams 5 times during the trial. A different brand of stapler performs the same test; it jams 22 times. | 100 Staple | Times / Usage |
| 7. Cockroaches are exposed to a pesticide. After 3 hours, 95% of the insects are dead. | Pesticide | Percentages / Numbers |
| 8. Two plants are grown using the same light and pots. One plant is given water that has been microwaved and the other plant is given regular tap water. Their height is measured after 2 weeks. | Microwaved Water | Height |

Final Answer:

For Scenario 3:
- Independent Variable: Salt Water
- Dependent Variable: Mass

$$
\boxed{\text{Salt Water, Mass}}
$$