Success: distinguish a full group from a sample and note practical/ethical limits. (AC9M8ST01, AC9M8ST04)
- Frame · 2 min. Read fictional question: “What travel modes occur in the imagined 100-student population?” No real classmates are surveyed.
- Model · 4 min. Define population 100, census all 100, sample fewer. A census gives full counts in this model but can be costly or intrusive in a real school.
- Guided classify · 5 min. Learners label A/B as constructed simple random samples of 20 and C as convenience sample of 20 by racks.
- Independent plan · 7 min. Write a way to select 20 from numbered fictional cards giving each one a known equal chance, without replacing selected cards. State one privacy question a real survey would need to resolve.
- Peer audit · 4 min. Partner checks whether selection location favours a mode and whether all 100 could be reached by the proposed method.
- Exit · 3 min. “Does 20 responses automatically mean a fair sample?” Key: no; how people were selected matters.