Research summaries: design, tools and measurement
Compare related experiments by identifying what changed, what was measured and what was held constant.
What you will tackle
- Identify hypotheses, variables, controls and replication
- Interpret tools, procedures, accuracy and precision
- Compare related experiments and propose modifications/extensions
- Distinguish an experimental control from controlled variables
Map the design before reading the result
The independent variable is deliberately changed; the dependent variable is the measured response. Controlled variables are held comparable. A control condition provides a reference, such as zero treatment. Repeated trials reveal variability. Repeating the same systematic measurement error does not remove it.
Tools determine what can be measured
A ruler measures length, a balance measures mass, a thermometer measures temperature and a graduated volume device measures volume. Precision concerns the consistency or resolution of measurements; accuracy concerns closeness to an accepted value. Comparing experiments requires checking both their changed factor and differences in apparatus or conditions.
Build your notes, then practise
Work on paper before opening an explanation. Guided tasks provide a starting point; independent tasks remove the scaffolding; application tasks ask you to justify a method or interpretation in context.
Guided practice
Guided 1
Experiment 1 compares cart travel on three surfaces at one ramp height. Experiment 2 repeats those surfaces at a greater height. Both measure distance with the same ruler and repeat each condition. Identify the changed variables within each experiment, between experiments, and a useful comparison.
Show a starting hint
Separate changes within a table from changes between tables.
Compare with the explained answer
- Within each experiment, surface is changed and travel distance is measured.
- Between experiments, ramp height changes.
- Compare the same surface across heights or surfaces at a fixed height, keeping the other factor explicit.
Answer / response criteria: Within: surface → distance; between: height; compare matched conditions to isolate a factor.
Independent practice
Independent 1
A balance reads 1.8,1.8,1.9 g for a certified 2.0 g mass. Assess consistency and possible accuracy. Would taking 100 readings necessarily correct the problem?
Compare with the explained answer
- The readings cluster closely, showing reasonable repeat consistency at this resolution.
- They are below the certified value, suggesting possible systematic under-reading.
- More readings can characterise variability but do not by themselves recalibrate the instrument.
Answer / response criteria: Consistent but potentially inaccurate; repetition alone does not correct a systematic offset.
Application practice
Application 1
A researcher changes both light and temperature and finds greater plant growth. Propose a design modification to distinguish their effects, and name a suitable measurement and safety limitation.
Compare with the explained answer
- Use matched plants in combinations of light/temperature conditions so each factor can be compared while the other is fixed.
- Measure growth by a defined length or mass outcome over the same period, with replication.
- Use supplied data or an approved supervised setup; the written plan is not proof of practical competence.
Answer / response criteria: A replicated factorial or matched comparison, with defined growth measurements and supervised practical arrangements.
What can you explain now?
A researcher changes both light and temperature and finds greater plant growth. Propose a design modification to distinguish their effects, and name a suitable measurement and safety limitation.
Compare with the explanation
A replicated factorial or matched comparison, with defined growth measurements and supervised practical arrangements.
Explain the reasoning before comparing. This review records your self-assessment rather than an official score or mastery decision.
After trying it yourself, choose your next review. This is your self-assessment.
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Source and review status
Coverage follows the named requirements and examples in the 2026–2027 ACT test guide and subject descriptions. That guide explicitly does not list every possible topic. The broader coded College and Career Readiness Standards are also mapped to conceptual teaching and practice; this does not calibrate a learner to a score band. The separate scientific-background context list and reading-complexity rubric have their own stated limits.
Original teaching and explained self-check practice are available. Specialist review and difficulty calibration remain pending. Essays require self-check or teacher review and are not automatically marked or awarded official scores.
Official source specification / guide