ILEARN Science Investigation 3 — Questions and Answers
Question 1: A scientist observes that plants near a window grow taller than plants in a dark corner. What is the best next step?
- Conclude that light causes plant growth
- Form a hypothesis and design a controlled experiment (Correct answer)
- Write a report stating light is essential
- Move all plants to the window immediately
Correct answer: Form a hypothesis and design a controlled experiment
An observation leads to a hypothesis, which must then be tested through a controlled experiment.
Question 2: In an experiment testing how fertilizer affects plant height, what is the dependent variable?
- Amount of fertilizer added
- Type of soil used
- Height of the plant (Correct answer)
- Amount of water given
Correct answer: Height of the plant
The dependent variable is what is measured — plant height — which depends on the fertilizer amount.
Question 3: A student creates a model of the water cycle. What is the main limitation of using a model in science?
- Models are always exactly like the real thing
- Models may not include every detail of the real system (Correct answer)
- Models cannot be used to make predictions
- Models are only useful for simple topics
Correct answer: Models may not include every detail of the real system
Models simplify reality and may leave out some details, which is their key limitation.
Question 4: Which safety rule is most important when heating a substance in a test tube?
- Point the opening away from people (Correct answer)
- Hold the test tube with bare hands
- Fill the test tube completely full
- Heat only at the bottom of the test tube
Correct answer: Point the opening away from people
Pointing the test tube away from people prevents injury if the substance suddenly boils or splatters.
Question 5: A student hypothesizes that adding salt to water will raise its boiling point. After testing, the data does not support the hypothesis. What should the student conclude?
- The experiment was done wrong and must be redone
- The hypothesis was not supported and should be revised (Correct answer)
- The data must be incorrect since the hypothesis made sense
- The student should change the data to match the hypothesis
Correct answer: The hypothesis was not supported and should be revised
When data does not support a hypothesis, scientists revise or reject the hypothesis based on evidence.
Question 6: What does a control group provide in a science experiment?
- The group that receives the highest dose of the variable
- A baseline for comparison that does not receive the treatment (Correct answer)
- The group where all variables are changed
- The group with the most participants
Correct answer: A baseline for comparison that does not receive the treatment
A control group is the standard for comparison — it does not receive the experimental treatment.
Question 7: Why is it important to use standard units (like meters and grams) when recording scientific data?
- Standard units are easier to write down
- They allow scientists around the world to compare results (Correct answer)
- They make measurements look more official
- Standard units are required only for chemistry experiments
Correct answer: They allow scientists around the world to compare results
Standard units allow scientists worldwide to understand, compare, and replicate each other's measurements.
ILEARN Science Investigation 3
A scientist observes that plants near a window grow taller than plants in a dark corner.
What is the best next step?