Study guide: Plants and fair comparisons
Read plant records and plan a comparison that supports a careful claim.
Ideas to explain in your own words
- Identify a comparison that changes one condition while keeping others the same.
- Distinguish starting height, final height, and growth.
- Use repeated observations to see variation within a group.
- Connect a changed condition, a recorded outcome, and a cautious conclusion.
Watch your reasoning
- The light condition changes while water and soil stay the same. Changing several conditions would make it harder to explain a result; changing none would not compare light levels.
- Growth is final minus starting height. A’s change is 3 cm and B’s is 2 cm.
- The yes counts are two and one. A3 is no and B2 is yes, so claims about all or none would misread the notes.
- The totals are 7 cm and 4 cm for equal-sized groups. This small supplied comparison does not establish a universal growth rule.
A worked review example
Read a Fair Plant Test: A and B help test the effect of water because light was the same. They do not separately test the effect of light. Measure the Recorded Change: A: 7 − 4 = 3 cm. B: 8 − 6 = 2 cm. A grew 1 cm more during this recorded week; B’s final height is still 1 cm greater. Look at More Than One Plant: Two of three planned-water seedlings and one of three low-water seedlings had new leaves. The groups differed by one yes result; neither group had identical results for all its plants. Plan a Test and Bound a Claim: The longer-light values sum to 7 cm across three plants; the shorter-light values sum to 4 cm. The longer-light group recorded more total growth, with overlap at 2 cm, so repeating the comparison would help check the pattern.
Make a practice plan
- Try the supplied lesson problems without looking at the answers.
- Compare your method with the worked examples and explain any correction.
- Use the new review cases, then complete the transfer task on paper or in your own document.