AZSCI Planning Investigations 1 — Questions and Answers
Question 1: A student wants to test how the amount of sunlight affects the height of a bean plant. What is the independent variable in this investigation?
- The final height of the bean plant.
- The amount of sunlight the plant receives. (Correct answer)
- The amount of water given to the plant each day.
- The type of soil used for the plant.
Correct answer: The amount of sunlight the plant receives.
The independent variable is the one factor that the investigator intentionally changes or manipulates to observe its effect. In this case, the student is purposefully changing the amount of sunlight.
Question 2: A group of students is designing an experiment to see which brand of paper towel is the most absorbent. Which of the following is the most important variable to keep constant (controlled) for each trial?
- The brand of paper towel.
- The amount of liquid poured onto the paper towel. (Correct answer)
- The amount of liquid absorbed by the paper towel.
- The time of day the experiment is conducted.
Correct answer: The amount of liquid poured onto the paper towel.
To ensure a fair test, all conditions except the one being tested (the brand of paper towel) must be kept the same. Pouring the same amount of liquid on each brand is critical for a valid comparison of absorbency.
Question 3: A scientist wants to investigate the effect of different types of fertilizer on the number of tomatoes produced by a plant. Which tool would be LEAST useful for collecting data in this investigation?
- A scale to weigh the tomatoes.
- A notebook to record the number of tomatoes.
- A ruler to measure plant height.
- A telescope to observe the plants. (Correct answer)
Correct answer: A telescope to observe the plants.
A telescope is used for observing distant objects, like stars and planets. It would not be a practical or useful tool for observing tomato plants in a garden or lab setting. The other tools are directly relevant to measuring plant growth and yield.
Question 4: When planning an investigation to test the freezing point of saltwater solutions, what is the best way to ensure the results are reliable?
- Use only one concentration of salt.
- Conduct the experiment only one time.
- Perform multiple trials for each salt concentration. (Correct answer)
- Measure the temperature in Fahrenheit instead of Celsius.
Correct answer: Perform multiple trials for each salt concentration.
Reliability in a scientific investigation is increased by repeating trials. This helps to ensure that the results are not due to chance or a single error, and allows for the calculation of an average, which is a more trustworthy value.
Question 5: A student hypothesizes that a heavier ball will roll down a ramp faster than a lighter ball. To test this, they plan to release two balls of different masses but the same size from the top of a ramp. What is the dependent variable?
- The mass of the ball.
- The height of the ramp.
- The time it takes the ball to reach the bottom. (Correct answer)
- The material the ramp is made of.
Correct answer: The time it takes the ball to reach the bottom.
The dependent variable is the factor that is measured or observed in response to the change in the independent variable. In this case, the student is changing the mass (independent variable) and measuring the time it takes to roll down (dependent variable).
Question 6: Which of the following is the best reason for creating a detailed, step-by-step procedure before starting an investigation?
- To make the experiment seem more professional and scientific.
- To ensure that other scientists can replicate the experiment exactly. (Correct answer)
- To guarantee that the hypothesis will be proven correct.
- To prevent any unexpected results from occurring.
Correct answer: To ensure that other scientists can replicate the experiment exactly.
A key principle of science is that experiments must be replicable. A detailed procedure allows other researchers to follow the same steps to verify the results, which is essential for building scientific knowledge.
Question 7: A student is investigating how the angle of a ramp affects the distance a toy car travels after it leaves the ramp. Which plan describes the most systematic way to carry out this investigation?
- Test many different cars on many different ramp angles all at once.
- Test one car on one angle, then a different car on a different angle.
- Test one car, releasing it from the same point, on a ramp set at specific, measured angles (e.g., 10°, 20°, 30°), and measure the distance for each angle. (Correct answer)
- Set the ramp at a random angle, roll the car, and then change the starting point on the ramp for the next trial.
Correct answer: Test one car, releasing it from the same point, on a ramp set at specific, measured angles (e.g., 10°, 20°, 30°), and measure the distance for each angle.
A systematic investigation involves changing only one variable at a time (the ramp angle) while keeping others constant (the car, the release point) and taking measurements at regular, planned intervals (e.g., 10°, 20°, 30°).
AZSCI Planning Investigations 1
A student wants to test how the amount of sunlight affects the height of a bean plant.
What is the independent variable in this investigation?