1. Two groups of sixth graders were tested to compare their speed in solving long division problems. One group had calculators, the other didn't.
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Dependent variable: Speed in solving long division problems
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Independent variable: Use of calculators (yes or no)
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Control variable: Sixth-grade students (same grade level), same type of math problem (long division)
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2. Students of different grades were given the same jigsaw puzzle to assemble. The time they took to assemble it was measured.
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Dependent variable: Time taken to assemble the puzzle
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Independent variable: Grade level of students
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Control variable: Same jigsaw puzzle
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3. Sasha wanted to figure out what type of liquid worked best for growing beans. She watered one with coca-cola, one with lemonade, and one with just water. After one week, she measured how high they had grown.
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Dependent variable: Height of bean plants
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Independent variable: Type of liquid used (coca-cola, lemonade, water)
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Control variable: Type of bean seeds, amount of liquid given, light exposure, soil type, pot size, temperature
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4. Miss Kobayashi wanted to find out what fertilizer works best in growing Marigolds. He put Miracle Grow on the first pot of Marigold, then Scotts Fertilizer on the second pot of Marigold, and no fertilizer on the third pot.
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Dependent variable: Growth of Marigolds (height or health)
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Independent variable: Type of fertilizer used (Miracle Grow, Scotts Fertilizer, none)
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Control variable: Same type of Marigold plant, same amount of water, same sunlight, same soil, same pot size
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5. Luffy wanted to see if eating apples would help him do better on his classwork. The first day, he didn’t eat any apples. On the 2nd day, he ate one apple; on the 3rd day, he ate 2 apples; and on the 4th day, he ate 3 apples. Each day, he recorded the grades he got on his science work.
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Dependent variable: Grades on science work
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Independent variable: Number of apples eaten per day
*(Note: No control variable is explicitly mentioned, but implied controls could include same subject tested, same teacher, same difficulty level of test, same amount of study time.)*
Parent Tip: Review the logic above to help your child master the concept of variables practice worksheet.
