Variables, Controls & Repeated Trials — Practice · Grade 6 Science
Chapter: Inquiry, Measurement & ModelsWhat this practice covers
By the end of Variables, Controls & Repeated Trials you should be able to:
- I can name the independent, dependent and controlled variables in an investigation.
- I can explain why a control group is needed even when the treatment obviously works.
- I can explain what repeating a trial tells you that one trial cannot.
8 questions, written answer and multiple choice, each with a worked explanation.
Vocabulary used: independent variable, dependent variable, evidence, system boundary, uncertainty.
Problem 1
Answer and explanation
The number of identical counters held before collapse, using the stated placement and failure rule.
Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.
Problem 2
Answer and explanation
Strip width and material or thickness. Use the same material and thickness while varying width if width is the intended factor.
Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.
Problem 3
Answer and explanation
Keeping all planned trials represents the observed variation and prevents selecting only the result that favors a claim.
Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.
Problem 4
Answer and explanation
No. It supplies a reference treatment, but the other influential conditions and measurement procedure must still be comparable.
Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.
Problem 5
Answer and explanation
Width and length both change. Length can affect bending, so the larger load does not isolate width. Keep length, material, support spacing, and counter placement the same, vary width, and use several fresh strips for each treatment. Compare all recorded loads under the same failure rule.
Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.
Problem 6
Answer and explanation
No. Counter count is not comparable when counter mass differs. Use identical counters or measure load mass, then repeat the corrected method.
Compare the scientific meaning and reasoning after an independent attempt. A different accurate supported response can be correct; human review is required.
Problem 7
- Repeating a confounded test makes its causal claim valid.
- independent variable: The factor deliberately changed for the intended comparison.
- A control treatment automatically keeps every other condition equal.
- One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation
independent variable: The factor deliberately changed for the intended comparison.
The factor deliberately changed for the intended comparison. Width and length both change. Length can affect bending, so the larger load does not isolate width. Keep length, material, support spacing, and counter placement the same, vary width, and use several fresh strips for each treatment. Compare all recorded loads under the same failure rule.
Problem 8
- A control treatment automatically keeps every other condition equal.
- Repeating a confounded test makes its causal claim valid.
- dependent variable: The response measured under the stated method.
- One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation
dependent variable: The response measured under the stated method.
The response measured under the stated method. Width and length both change. Length can affect bending, so the larger load does not isolate width. Keep length, material, support spacing, and counter placement the same, vary width, and use several fresh strips for each treatment. Compare all recorded loads under the same failure rule.