Observe, compare and group
Use the supplied evidence and a consistent rule. These models teach a grouping method, not species identification
- Two separate features Teeth are small points on an edge. Lobes are broad parts separated by deeper gaps. Smooth lobed leaves have lobes without teeth
- One rule Check the named feature for every sample. Ignore unrelated features unless the rule also asks for them
- Both conditions A sample must meet each condition. Meeting only one is not enough
- Keep the claim limited A shared feature supports a group under that rule. It does not by itself establish a species or an evolutionary relationship
Worked example
An observer recorded two features of some leaf samples. Use the records below. The letters label samples, not species
| Sample | Edge | Outline (lobing) |
|---|---|---|
| A | toothed | unlobed |
| B | smooth | lobed |
| C | smooth | unlobed |
| D | toothed | lobed |
| E | toothed | unlobed |
Grouping rule: include a sample if it has both a smooth edge and a lobed outline
Which leaf samples meet the rule? Select all that do, and no others
Check each record for both a smooth edge and a lobed outline. Both means that each included sample must meet both conditions, not just one
Sample A: toothed edge, unlobed outline. Exclude it because neither required feature matches
Sample B: smooth edge, lobed outline. Include it because both required features match
Sample C: smooth edge, unlobed outline. Exclude it because only the edge matches; the outline does not
Sample D: toothed edge, lobed outline. Exclude it because only the outline matches; the edge does not
Sample E: toothed edge, unlobed outline. Exclude it because neither required feature matches
Select B and no other samples
Difficulty levels
Questions about this topic
Is there only one correct way to group a collection?+
No. Different stated rules can produce different useful groups. Once a rule is chosen, apply it consistently to every sample
Does smooth mean a leaf has no lobes?+
No. Here smooth means no small edge teeth. A leaf can still have broad lobes separated by deep gaps
Does this finish biological classification?+
No. Identification keys come next. Observing real specimens, choosing useful features and writing explanations also need practice beyond these objective checks
Can I use a calculator?+
No. This topic is practised without a calculator
Which year level and chapter is this?+
Year 7 Science, chapter 2: Biological sciences