Reading & writing · Grades 7–10
The lighting comparison · reading guide
An original passage with comprehension, reasoning and a marking guide.
The lighting comparison
For one week, a science class measured electricity use in two rooms with different lighting systems. The room with newer lights used less electricity. However, that room also had larger windows and was empty for two afternoons. The class revised its conclusion: the observations suggested a difference, but the test did not isolate the effect of the lights.
Read, think and respond
- Name one factor other than the lighting system that differed.
- Why can the class not attribute the entire difference to the lights?
- Propose one improvement to the investigation.
Suggested answers and marking notes
Name one factor other than the lighting system that differed.
Rubric: Identify window size or afternoon occupancy.
Why can the class not attribute the entire difference to the lights?
Rubric: Explain confounding: daylight or time occupied could also affect use. The comparison changed more than one relevant factor.
Propose one improvement to the investigation.
Rubric: Suggest controlling occupancy or daylight, alternating systems in the same room, or making matched repeated measurements. Explain which confound it addresses.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.