All lessons › Challenge: Food web detectives › Lesson 1
Australian primary science · Years 5–6 (challenge) · Lesson 1 of 3
The cane toad mystery
Inquiry question: How can one new animal change a whole food web?
Marked no materials needed
Using a model
What students learn
A food web shows many linked food chains. A change to one population can ripple along the arrows, affecting animals two or three steps away, sometimes in surprising directions.
Success criteria
- I can follow arrows in a food web to find who eats whom.
- I can predict a two-step ripple effect and give a reason.
- I can explain why some predictions about food webs are surprising.
Preparation and materials
Before this lesson: Students can read a food chain and know that habitat changes affect survival (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 › Lab › Food web what-ifs 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.
- Pairs finish a set of what-ifs in Food web what-ifs, writing a ‘because’ for each prediction before checking.
- Read the source sheet about cane toads.
- Draw a food web on the iPad or paper with at least six living things from the source, including the cane toad.
- Predict what happens to each population after the toads arrive, and how sure you are.
- Write one question scientists could test to check one of your predictions.
Teacher modelling prompt
Open Food web what-ifs on the big screen. Read one what-if aloud (they come in a random order), then model the drought one. Think aloud: “The arrow goes from grass to kangaroo, so kangaroos eat grass. If grass goes down, kangaroos lose food, so they probably go down too. Then dingoes, which eat kangaroos, go down later.” Point out that the ripple is two steps.
Record and explain evidence
Recording question: How can one new animal change a whole food web?
| Population | Prediction (up, down or same) | Because… | How many steps from the cane toad? |
|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Who has used the whole food web, not just one arrow?
Check understanding
What should pupils know? What does a food web show that a single food chain doesn’t?
Explain with evidence: Explain how cane toads could make a population of insects go up, using two arrows from the food web.
Apply the idea: Before releasing a new animal to control a pest, what should scientists find out first? Give one reason.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.