All lessons › Challenge: Food web detectives › Lesson 3
Australian primary science · Years 5–6 (challenge) · Lesson 3 of 3
Key to the creatures
Inquiry question: How can a set of yes-or-no questions identify any animal?
Marked no materials needed
Classifying
What students learn
Scientists group living things by shared features (classification). A dichotomous key uses a series of two-way questions about observable features to identify a living thing. Good keys use features you can see, not opinions.
Success criteria
- I can sort animals into groups using features I can observe.
- I can build a key with yes-or-no questions that identifies each animal.
- I can test a classmate’s key and suggest an improvement.
Preparation and materials
Before this lesson: Students know structural features help animals survive (Survival in habitats).
- iPads with Bottlebrush Education open (nothing else needed) — 13 (one per pair)
- Projector or big screen — 1
Teacher setup
- Open Living things › Play › Creature clues on your screen to demonstrate.
- Check the iPads are charged and set to Your year › Years 5–6.
Safety and adaptations
Follow school science and equipment risk assessment procedures for the materials used.
Review your school policies and curriculum requirements before teaching.
How to investigate
The lesson sequence should leave pupils with evidence to interpret, not only an activity to finish.
- Play Creature clues to warm up on animal groups.
- Read the source sheet. Sort the eight animals into groups using features only.
- Build a dichotomous key that gives every animal its own ending. Draw it as a branching diagram or numbered questions.
- Swap keys with another pair. Test it on three animals, without help.
- Write feedback: one question that worked, and one that could be clearer or more observable.
Teacher modelling prompt
Draw the first branch of a key on the board using the source animals. Think aloud: “Does it have a backbone? Yes: platypus, kookaburra, emu, blue-tongue, green tree frog, red kangaroo. No: redback spider, Ulysses butterfly. Now I need a question that splits the ‘no’ group in two: ‘Does it have eight legs?’ Yes is the redback.” Point out that ‘Is it scary?’ would be a bad question: people disagree.
Record and explain evidence
Recording question: How can a set of yes-or-no questions identify any animal?
| Question number | Question (yes or no) | If yes, go to… | If no, go to… | Is it observable? (yes or no) |
|---|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Which question is more reliable for any bird, and why?
Check understanding
What should pupils know? What makes a good question in a dichotomous key?
Explain with evidence: A key asks, “Is it a fast runner?” Explain why this is a weak question and write a better one.
Apply the idea: A new animal has a backbone, smooth moist skin and lays eggs in water. Use your key to place it, and name its group.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.