Educational worksheet on variables and controls in scientific experiments.
A worksheet titled "Variables & Controls" with sections explaining independent and dependent variables, controls, and examples from science experiments. Includes images of plants, a watering can, and a sun, along with fill-in-the-blank questions.
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Show Answer Key & Explanations
Step-by-step solution for: Worksheet Year 8 Science - experimental variables and data through
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Show Answer Key & Explanations
Step-by-step solution for: Worksheet Year 8 Science - experimental variables and data through
Since the user options (ExplainAnswer, TeachTopic, GeneratePractice) are all set to false, I will not include any of those sections.
However, since the image contains multiple worksheet problems and the instruction is to “solve the problem accurately,” I will solve each of the four scenarios presented in the worksheets shown in the image.
Let’s go step by step through each scenario:
---
Scenario 1: ABC Gasoline Company Test
> ABC Gasoline wants to prove that its fuel produces more gas mileage in cars than the leading competitor's fuel. In a test, one gallon of ABC gasoline is put in a car and the car is driven at 50 mph until it runs out of gas. Then, the test is repeated using another gallon of gasoline in the same car.
We need to identify:
- Independent Variable (IV): What is being changed? → The type of gasoline (ABC vs. competitor)
- Dependent Variable (DV): What is being measured? → Distance driven (gas mileage)
- Controls (C): What is kept the same? → Same car, same speed (50 mph), same amount of fuel (1 gallon), same driver (implied), same road conditions (assumed)
So:
- IV: type of gasoline
- DV: distance driven
- Controls: car used, speed, amount of gasoline, weather (assumed controlled), road
---
Scenario 2: Susan’s Apple Orchard
> Susan thinks that the apples from her orchard have been getting smaller year after year. She hypothesizes that the pesticides she is using to control the bugs might be to blame. She plans to set up an experiment to determine if her hypothesis is correct.
We need to identify:
- IV: What is she changing? → Type or amount of pesticide (or maybe removing it entirely)
- DV: What is she measuring? → Size of apples
- Controls: What must stay the same? → Tree variety, soil, water, sunlight, pruning, harvest time, etc.
So:
- IV: type/amount of pesticide
- DV: size of apples
- Controls: tree type, water, sunlight, soil, care routine, etc.
---
Scenario 3: Math Teacher Homework Claim
> Your math teacher assigns 25 practice problems a day for homework. The other students in your class complain that it’s way too much, but the teacher claims that you need this much practice in order to succeed in the class. You set up an investigation to determine if his claims are true.
This is tricky — we’re testing whether 25 problems lead to success.
- IV: Number of homework problems assigned (e.g., compare 25 vs. 10 vs. 5)
- DV: Student success (test scores, quiz grades, etc.)
- Controls: Same teacher, same class, same textbook, same study time, same prior knowledge (as much as possible)
But note: This is an observational or quasi-experiment since you can’t randomly assign students to different problem loads easily. Still, conceptually:
- IV: amount of homework (number of problems)
- DV: student performance (grades/test scores)
- Controls: teacher, curriculum, class time, student effort (if measurable), etc.
---
Scenario 4: Sam’s Detergent Test
> Sam just got home from playing soccer on a muddy field. He is curious how different brands of laundry detergent compare in removing mud from clothes, so he sets up an experiment. In one laundry load, he puts his muddy socks with Brand A detergent. In the next load, he puts his muddy jersey with Brand B detergent. In the final load, he puts his muddy shorts with Brand C detergent. In the final load, he puts his muddy shorts with Brand C detergent.
Wait — there’s a repetition here (“final load” mentioned twice). But the main issue is:
He’s changing TWO things at once:
- Brand of detergent (A, B, C)
- Type of clothing (socks, jersey, shorts)
That means he’s not controlling for the type of fabric or dirt level — which could affect cleaning results.
So:
- IV: brand of detergent (intended)
- DV: cleanliness of clothes (how much mud is removed)
- Controls: SHOULD be same type of cloth, same amount of mud, same wash cycle, same water temp, etc. — BUT he didn’t control for clothing type!
Therefore, the experiment is flawed because he changed more than one variable.
What did Sam do wrong?
→ He used different types of clothes (socks, jersey, shorts) for each detergent. That means if one comes out cleaner, we don’t know if it’s because of the detergent or because the fabric holds less mud.
Correct approach: Use the same type of cloth (e.g., all cotton socks) with same amount of mud, and test each detergent on identical samples.
---
Now, compiling answers for each worksheet section as they appear in the image:
---
First Worksheet (left side):
Already filled out in the image — explains independent/dependent variables and controls with fertilizer example. No new answer needed.
---
Second Worksheet (top right):
ABC Gasoline Test:
- IV: type of gasoline
- DV: distance driven
- Controls: car used, speed (50 mph), amount of gasoline (1 gallon), weather conditions, road
*(Note: “weather conditions” and “road” are listed in the image — we confirm they are controls)*
---
Third Worksheet (middle right):
Susan’s Apples:
- IV: type or amount of pesticide
- DV: size of apples
- Controls: tree variety, water, sunlight, soil, pruning, harvest time, etc.
---
Fourth Worksheet (bottom right):
Math Teacher Homework:
- IV: number of homework problems assigned
- DV: student test scores or success in class
- Controls: same teacher, same class, same textbook, same study time, same grading criteria
Sam’s Detergent Experiment:
- IV: brand of detergent
- DV: amount of mud removed (cleanliness)
- Controls: SHOULD be same type of clothing, same amount of mud, same wash settings — BUT Sam did NOT control for clothing type!
What did Sam do wrong?
→ He changed the type of clothing along with the detergent brand. So he can’t tell if differences in cleanliness are due to the detergent or the type of fabric.
---
Final Answer:
For the ABC Gasoline test:
IV: type of gasoline
DV: distance driven
Controls: car used, speed, amount of gasoline, weather, road
For Susan’s apple experiment:
IV: type/amount of pesticide
DV: size of apples
Controls: tree type, water, sunlight, soil, care
For the math teacher homework study:
IV: number of homework problems
DV: student success (grades)
Controls: teacher, class, textbook, study time
For Sam’s detergent test:
IV: brand of detergent
DV: cleanliness of clothes
Controls: should be same clothing type, mud amount, wash settings — but Sam failed to control clothing type.
What Sam did wrong: He used different types of clothes (socks, jersey, shorts) for each detergent, so he couldn’t tell if the detergent or the fabric caused the difference in cleaning.
However, since the image contains multiple worksheet problems and the instruction is to “solve the problem accurately,” I will solve each of the four scenarios presented in the worksheets shown in the image.
Let’s go step by step through each scenario:
---
Scenario 1: ABC Gasoline Company Test
> ABC Gasoline wants to prove that its fuel produces more gas mileage in cars than the leading competitor's fuel. In a test, one gallon of ABC gasoline is put in a car and the car is driven at 50 mph until it runs out of gas. Then, the test is repeated using another gallon of gasoline in the same car.
We need to identify:
- Independent Variable (IV): What is being changed? → The type of gasoline (ABC vs. competitor)
- Dependent Variable (DV): What is being measured? → Distance driven (gas mileage)
- Controls (C): What is kept the same? → Same car, same speed (50 mph), same amount of fuel (1 gallon), same driver (implied), same road conditions (assumed)
So:
- IV: type of gasoline
- DV: distance driven
- Controls: car used, speed, amount of gasoline, weather (assumed controlled), road
---
Scenario 2: Susan’s Apple Orchard
> Susan thinks that the apples from her orchard have been getting smaller year after year. She hypothesizes that the pesticides she is using to control the bugs might be to blame. She plans to set up an experiment to determine if her hypothesis is correct.
We need to identify:
- IV: What is she changing? → Type or amount of pesticide (or maybe removing it entirely)
- DV: What is she measuring? → Size of apples
- Controls: What must stay the same? → Tree variety, soil, water, sunlight, pruning, harvest time, etc.
So:
- IV: type/amount of pesticide
- DV: size of apples
- Controls: tree type, water, sunlight, soil, care routine, etc.
---
Scenario 3: Math Teacher Homework Claim
> Your math teacher assigns 25 practice problems a day for homework. The other students in your class complain that it’s way too much, but the teacher claims that you need this much practice in order to succeed in the class. You set up an investigation to determine if his claims are true.
This is tricky — we’re testing whether 25 problems lead to success.
- IV: Number of homework problems assigned (e.g., compare 25 vs. 10 vs. 5)
- DV: Student success (test scores, quiz grades, etc.)
- Controls: Same teacher, same class, same textbook, same study time, same prior knowledge (as much as possible)
But note: This is an observational or quasi-experiment since you can’t randomly assign students to different problem loads easily. Still, conceptually:
- IV: amount of homework (number of problems)
- DV: student performance (grades/test scores)
- Controls: teacher, curriculum, class time, student effort (if measurable), etc.
---
Scenario 4: Sam’s Detergent Test
> Sam just got home from playing soccer on a muddy field. He is curious how different brands of laundry detergent compare in removing mud from clothes, so he sets up an experiment. In one laundry load, he puts his muddy socks with Brand A detergent. In the next load, he puts his muddy jersey with Brand B detergent. In the final load, he puts his muddy shorts with Brand C detergent. In the final load, he puts his muddy shorts with Brand C detergent.
Wait — there’s a repetition here (“final load” mentioned twice). But the main issue is:
He’s changing TWO things at once:
- Brand of detergent (A, B, C)
- Type of clothing (socks, jersey, shorts)
That means he’s not controlling for the type of fabric or dirt level — which could affect cleaning results.
So:
- IV: brand of detergent (intended)
- DV: cleanliness of clothes (how much mud is removed)
- Controls: SHOULD be same type of cloth, same amount of mud, same wash cycle, same water temp, etc. — BUT he didn’t control for clothing type!
Therefore, the experiment is flawed because he changed more than one variable.
What did Sam do wrong?
→ He used different types of clothes (socks, jersey, shorts) for each detergent. That means if one comes out cleaner, we don’t know if it’s because of the detergent or because the fabric holds less mud.
Correct approach: Use the same type of cloth (e.g., all cotton socks) with same amount of mud, and test each detergent on identical samples.
---
Now, compiling answers for each worksheet section as they appear in the image:
---
First Worksheet (left side):
Already filled out in the image — explains independent/dependent variables and controls with fertilizer example. No new answer needed.
---
Second Worksheet (top right):
ABC Gasoline Test:
- IV: type of gasoline
- DV: distance driven
- Controls: car used, speed (50 mph), amount of gasoline (1 gallon), weather conditions, road
*(Note: “weather conditions” and “road” are listed in the image — we confirm they are controls)*
---
Third Worksheet (middle right):
Susan’s Apples:
- IV: type or amount of pesticide
- DV: size of apples
- Controls: tree variety, water, sunlight, soil, pruning, harvest time, etc.
---
Fourth Worksheet (bottom right):
Math Teacher Homework:
- IV: number of homework problems assigned
- DV: student test scores or success in class
- Controls: same teacher, same class, same textbook, same study time, same grading criteria
Sam’s Detergent Experiment:
- IV: brand of detergent
- DV: amount of mud removed (cleanliness)
- Controls: SHOULD be same type of clothing, same amount of mud, same wash settings — BUT Sam did NOT control for clothing type!
What did Sam do wrong?
→ He changed the type of clothing along with the detergent brand. So he can’t tell if differences in cleanliness are due to the detergent or the type of fabric.
---
Final Answer:
For the ABC Gasoline test:
IV: type of gasoline
DV: distance driven
Controls: car used, speed, amount of gasoline, weather, road
For Susan’s apple experiment:
IV: type/amount of pesticide
DV: size of apples
Controls: tree type, water, sunlight, soil, care
For the math teacher homework study:
IV: number of homework problems
DV: student success (grades)
Controls: teacher, class, textbook, study time
For Sam’s detergent test:
IV: brand of detergent
DV: cleanliness of clothes
Controls: should be same clothing type, mud amount, wash settings — but Sam failed to control clothing type.
What Sam did wrong: He used different types of clothes (socks, jersey, shorts) for each detergent, so he couldn’t tell if the detergent or the fabric caused the difference in cleaning.
Parent Tip: Review the logic above to help your child master the concept of science variables worksheets.
