Educational worksheet for students to learn about variables in scientific investigations.

Let’s go through each question one by one. We’re looking for:

- IV = Independent Variable (what the scientist changes on purpose)
- DV = Dependent Variable (what is measured or observed as a result)
- C = Control (things kept the same so they don’t affect the results)

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Question 1: ABC Gasoline 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 the competitor's gasoline in the same car on the same road.”

We need to mark IV, DV, and C beside the correct items.

List:
- the rival → This is part of the comparison, but not what’s being changed directly. The *type* of gasoline is what’s changing.
- the car used for the test → Same car used both times → this is kept constant → Control
- the brand of gasoline → This is what’s being changed (ABC vs competitor) → Independent Variable
- 50 mph → Speed is kept the same → Control
- the distance driven → This is what they measure — how far the car goes on one gallon → Dependent Variable
- weather conditions → Should be kept the same → Control

✔ So:

- the rival → (not labeled — it’s context, not a variable we control or measure directly here)
- the car used for the test → C
- the brand of gasoline → IV
- 50 mph → C
- the distance driven → DV
- weather conditions → C

*(Note: “the rival” isn’t really a variable — it’s just referring to the competitor’s gas. The actual IV is “brand of gasoline.”)*

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Question 2: Tina’s helmet aerodynamics test

> “Tina is conducting an investigation on bicycle helmet aerodynamics. She is trying to find out what kind of helmet causes the least amount of air resistance. She tested three different helmets, using the same rider each time, and recorded the time it took for the rider to complete one circuit on a track.”

What are the variables?

She’s testing different helmets → that’s what she’s changing → IV

She’s measuring time to complete one circuit → that’s what changes based on the helmet → DV

Everything else should stay the same:

- same rider → C
- same track → C
- probably same bike, same weather, etc. → also controls, but only listed options matter.

List:

- the time taken to complete one circuit on the track → DV
- the rider → C
- the kind of helmet → IV
- the track → C
- the bicycle → C (assumed same bike used)

✔ So:

- the time taken to complete one circuit on the track → DV
- the rider → C
- the kind of helmet → IV
- the track → C
- the bicycle → C

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Question 3: Autism and vaccines study

> “Autism is a disability that results from a disorder in the central nervous system. It has been speculated that the increasing number of cases of autism in recent years is due to the increase in vaccinations given to young children.”

They’re testing whether vaccines cause autism.

So, what’s being changed? → Whether or not children got vaccines → IV

What’s being measured? → Number of autism cases → DV

Other things that might affect autism rates but should be kept the same (or accounted for):

- age of children → if you compare kids of different ages, autism diagnosis might vary → should be controlled → C
- amount of vaccines given → this could be part of IV, but if they’re comparing “vaccinated vs not,” then amount might be a detail of IV. But since it says “increase in vaccinations,” maybe amount is part of IV. However, in this list, “amount of vaccines given” is separate from “health of children before vaccines.” Let’s think carefully.

Actually, the main idea: They want to see if getting vaccines leads to more autism.

So:

- IV: whether vaccines were given (or how many) → but in the list, we have:
- the age of the children → should be same group → C
- the amount of vaccines given → this could be the IV if they’re varying dose, but the speculation is about “increase in vaccinations” meaning more kids vaccinated or more doses. Since the next item is “number of cases of autism,” which is clearly DV, then “amount of vaccines given” is likely the IV.
- the diet of the children → could affect development → should be controlled → C
- the number of cases of Autism → DV
- the health of the children before the vaccines were given → important! If kids were already unhealthy, maybe that affects autism risk → must be controlled → C
- the tests used to determine if a child has Autism → must be same test for all → C

Wait — let’s re-read the speculation: “increasing number of cases... due to increase in vaccinations”

That suggests they’re comparing groups with different levels of vaccination exposure.

So:

→ IV: amount of vaccines given (more vaccines = higher exposure)

→ DV: number of autism cases

→ Controls: everything else that could influence autism rate — age, diet, pre-existing health, diagnostic method.

✔ So:

- the age of the children → C
- the amount of vaccines given → IV
- the diet of the children → C
- the number of cases of Autism → DV
- the health of the children before the vaccines were given → C
- the tests used to determine if a child has Autism → C

*(Note: Some might argue “amount of vaccines” is not precise — but in context, it’s the factor being tested as the cause.)*

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Now, compiling all answers clearly:

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Final Answer:

Question 1 (ABC Gasoline):

- the rival → (no label needed — not a variable in this setup)
- the car used for the test → C
- the brand of gasoline → IV
- 50 mph → C
- the distance driven → DV
- weather conditions → C

Question 2 (Helmet Test):

- the time taken to complete one circuit on the track → DV
- the rider → C
- the kind of helmet → IV
- the track → C
- the bicycle → C

Question 3 (Autism & Vaccines):

- the age of the children → C
- the amount of vaccines given → IV
- the diet of the children → C
- the number of cases of Autism → DV
- the health of the children before the vaccines were given → C
- the tests used to determine if a child has Autism → C