Teaching sequence

Lesson objective

In this lesson students create first-hand data of factors that affect population sizes such as seasonal changes, destruction of habitats and introduced species. They investigate models predicting the changes in populations due to environmental change, such as the impact of flooding or fire on rabbit or kangaroo populations and consider the impacts of human activity on an ecosystem from a range of different perspectives.


Discuss how the population of humans in the students’ local area has changed over the last 50 years. Consider any corresponding change in plant or animal populations.

Explore what evidence is available to support consideration of how the population has changed and discuss possible reasons for why it has changed. 


  1. Complete the activity Wildlife smarties (Word, 392 KB).
  2. Ask the students the following questions.  
    • What would happen if the marked animals migrated out of that ecosystem?
    • How would the estimated number of smarties be affected if the tagging slowed the animals down so that they were easier to capture by you or predators?
  3. Watch the video clip Guppy Mark–Recapture 1: Collecting guppies
  4. Ask the students the following question: What sort of things could affect the population of a species?
  5. Instruct students to draw a table with two columns in their books. Column one for things that will increase a population of rabbits and column two for things that will decrease a population of rabbits. Ask students to fill in the columns.
  6. Complete the game Rabbit and fox chasey. Based on what they learnt from the game, ask students to add to the table in their books.
    Teacher note: Instructions for this game can be found in Background information.
  7. Complete the Dugong dilemma assessment. A teacher guide for this learning object is also available.


Discuss the impact of introduced animals (eg Cane Toad) on the populations of insects, other frogs, snakes etc. Watch the video clip Taste training for northern quolls

Lesson Resources


Student activities

Digital resources

Guppy mark–recapture 1: collecting guppies, YouTube (6:14 min) 

L7734 Dugong dilemma assessment,  NDLRN. Learning object

R9248 Dugong dilemma: assessment: teacher guide, NDLRN 

Taste training for northern quolls, Australian Geographic. Article and
video clip. (Link updated, 16 December, 2016.)


Wildlife smarties (Word, 392 KB)

Extension activities

Is your body like an ecosystem? (Word, 326 KB)

Useful links

Experiment with ecosystems,
The Concord Consortium. Learning object 

Invasive species matching game,
Nova Online. Interactive game 

L1446 Ecosystem balance,
NDLRN. Learning object

The virtual ecosystem,
The Concord Consortium. Learning object