Experimental variables worksheet - Name: Date: - Studocu - Free Printable

Let's solve each of the three experimental scenarios step by step, identifying the Independent Variable (IV), Dependent Variable (DV), Constants, and Control based on the definitions provided:

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1) The number of flowers on different breeds of bushes in a greenhouse is recorded every week for two months.

- Independent Variable (IV):
*The breed of the bush*
→ This is what is being changed or varied by the experimenter (different breeds).

- Dependent Variable (DV):
*The number of flowers*
→ This is what is being measured (how many flowers each bush produces over time).

- Constants:
*Location (greenhouse), time interval (weekly), duration (two months), amount of sunlight, temperature, watering schedule, soil type, etc.*
→ These factors are kept the same across all bushes to ensure a fair test.

- Control:
*There is no explicit control group mentioned, but if one were included, it might be a standard or well-known bush breed used as a baseline. However, since the experiment compares different breeds, there may not be a true "control" unless one breed is specifically designated as the baseline. In this case, no clear control is stated, so we can say: *None explicitly stated* or *All breeds are part of the experimental groups.*

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2) You give four sunflowers different watering with either pure water or different concentrations of salt solutions. After a two-week period, the height is measured.

- Independent Variable (IV):
*Type of watering solution (pure water vs. different salt concentrations)*
→ This is what is deliberately changed.

- Dependent Variable (DV):
*Height of the sunflowers*
→ This is what is being measured after two weeks.

- Constants:
*Sunlight exposure, soil type, pot size, initial height/age of sunflowers, temperature, amount of water given (volume), time period (two weeks), etc.*
→ These should remain the same for all plants to isolate the effect of the solution.

- Control:
*The sunflower watered with pure water*
→ This serves as the baseline to compare against the salt-treated plants to see if salt affects growth.

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3) Three redwood trees are kept at different humidity levels inside a greenhouse for 12 weeks. One tree is left outside in normal conditions. Height of the tree is measured once a week.

- Independent Variable (IV):
*Humidity level*
→ The humidity varies among the trees inside the greenhouse.

- Dependent Variable (DV):
*Height of the tree*
→ Measured weekly to observe growth changes.

- Constants:
*Species of tree (redwood), age/size at start, light exposure, soil type, amount of water, temperature (if controlled), time period (12 weeks), measurement frequency (weekly), etc.*
→ These are kept consistent to isolate the effect of humidity.

- Control:
*The tree left outside in normal conditions*
→ This tree is not exposed to manipulated humidity and represents natural environmental conditions, serving as a comparison point.

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✔ Final Answers:

#### 1)
| Independent Variable (IV): | Breed of bush |
|---------------------------|---------------|
| Dependent Variable (DV): | Number of flowers |
| Constants: | Greenhouse location, lighting, temperature, watering, soil, time of recording |
| Control: | None explicitly stated (or all are experimental) |

#### 2)
| Independent Variable (IV): | Type of watering solution (pure water vs. salt solutions) |
|---------------------------|--------------------------------------------------------|
| Dependent Variable (DV): | Height of sunflowers |
| Constants: | Sunlight, soil, pot size, volume of water, plant age, temperature |
| Control: | Sunflower watered with pure water |

#### 3)
| Independent Variable (IV): | Humidity level |
|---------------------------|----------------|
| Dependent Variable (DV): | Height of the tree |
| Constants: | Tree species, age, soil, water amount, light, measurement frequency |
| Control: | Tree kept outside in normal conditions |

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🔍 Explanation Summary:

- IV: What you change.
- DV: What you measure.
- Constants: Everything else that stays the same.
- Control: A standard condition to compare against the experimental groups.

These answers follow scientific experimental design principles and help students understand how variables function in real-world experiments.