"Identifying Variables" worksheet from the "How To Train Your Dragon" series, designed to teach students about independent, dependent, and control variables in science experiments.

Let's solve the problem step by step by identifying the independent, dependent, and control variables in each scenario based on the definitions provided:

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🔹 Scenario 1:

> Two groups of fifth graders were tested to compare their speed solving long division problems. One group had calculators, the other didn't.

#### Definitions Recap:
- Independent variable: The factor that is changed (manipulated).
- Dependent variable: What is being measured or observed.
- Control variable: Factors kept constant to ensure a fair test.

#### Analysis:
- The only difference between the two groups is whether they had calculators.
- The outcome being measured is how fast they solved the problems (speed).
- The students are all fifth graders, so age/grade level is the same — this helps keep things consistent.

#### Answers:
- Dependent variable: Speed at which students solve long division problems
*(This is what is being measured.)*
- Independent variable: Use of calculators (yes/no)
*(This is what was changed.)*
- Control variable: Grade level (fifth grade), type of math problem (long division), number of problems, etc.
*(These factors were kept the same to ensure fairness.)*

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🔹 Scenario 2:

> Students of different grades were given the same jigsaw puzzle to assemble. The time they took to assemble it was measured.

#### Analysis:
- The grade level of the students varies (e.g., 3rd, 5th, 7th).
- The same puzzle was used for everyone.
- The time taken to complete the puzzle was recorded.

#### Answers:
- Dependent variable: Time taken to assemble the puzzle
*(This is what was measured.)*
- Independent variable: Grade level of the students
*(This is what was changed — different grades = different levels of experience or skill.)*
- Control variable: The jigsaw puzzle (same one for all), instructions, environment, etc.
*(These were kept constant to make the comparison fair.)*

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✔ Final Answers:

#### Scenario 1:
- Dependent variable: Speed solving long division problems
- Independent variable: Use of calculators
- Control variable: Grade level, type of problem, etc.

#### Scenario 2:
- Dependent variable: Time taken to assemble the puzzle
- Independent variable: Grade level of students
- Control variable: Type of puzzle, conditions of assembly, etc.

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💡 Summary Tip:

Always ask:
- What did we change? → Independent variable
- What did we measure? → Dependent variable
- What did we keep the same? → Control variable

Let me know if you'd like a printable version or more examples!