Moa - evidence or inference?

Moa - evidence or inference?

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This task is about the difference between evidence and inference.
Scientists think that moa lived very successfully in New Zealand for many hundreds of thousands of years and became extinct some time after the arrival of people. What we know about the moa comes mainly from scientists who look carefully for evidence and then use that to make inferences about what moa looked like and how they behaved.

Evidence is something that you can see or count.
An inference is a new idea based on what you have seen.
For example, moa bones have been found all over New Zealand. This is evidence that moa existed. We can see the bones.
An inference based on this evidence is that moa lived all over New Zealand.

a)  In your group sort the statements on cards into those that are evidence and those that are inferences. Match each inference card to its appropriate evidence card, and place them below.

evidence-inference-box-4-examples.png

Cut out the statements below, discuss in your group and put them in the table above.

Moa-evidence-inference-options.png

 
 
 
 
b) i)
Using the information from the cards, show a likely food chain for the moa before the arrival of people in New Zealand.
 
   
 
 
 
 
 
 
 
 
 
 
ii)
 
What evidence did you base your ideas on?
 
 
 
 
 
 
 
 
 
 
 
c)
Why do you think the moa became extinct after the arrival of people?
Give as many reasons as you can.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Task administration: 

Equipment

Information cards about Moa, and the task sheet.

  • It is suggested students work in small groups to complete this task.
  • Prepare the cards before the activity. Each group will need one set of cards and a copy of the task sheet.

 

Level:
4
Curriculum info: 
Science, Understanding about science, Living World
Keywords: 
evolution, extinction, moa, evidence, inference, group assessment
Description of task: 
Students categorise statements according to whether they are evidence or inferences. They make inferences about moa, supporting them with evidence. Assessment focus: thinking in scientific ways.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask.
 
Capability: Gather and interpret data
This resource provides opportunities to discuss:
  • how scientists gather data.
  • describing being about what you see, and explaining being about what your observations make you think.
 
Capability: Use evidence
This resource provides opportunities to discuss using evidence to make valid explanations.
 
Capability: Interpret representations
This resource provides opportunities to discuss putting data from text into food chains.
 
Science capabilities: 
Gather and interpret data, Interpret representations, Use evidence
Answers/responses: 

a)

  
Evidence Inference
The only fossil remains found to date of a large predator are those of the Haast eagle. There were few natural enemies so the moa would have needed few protective adaptations.
Smooth polished stones have been found with moa skeletons. Moa, like many other birds, swallowed stones to grind up food in their gizzards.
All gizzard stones scientists have found match the stones found nearby. Moa did not move around over large areas.
Preserved stomach contents found include twigs, leaves and berries. Moa lived in forest, not open grassland.
b)
i)
ii)
Forest vegetation      

     Moa      

 

      Haast eagle

Most likely food of adult moa was forest vegetation. Haast eagle was a likely predator.
Evidence: Stomach contents of Moa, fossil remains of Haast eagle.
c)   Previously moa had few enemies so they lacked adaptations for survival when humans arrived. Moa were killed for food, introduction of rats and dogs had an adverse effect and bush was cleared.

 

Diagnostic and formative information: 

In question b) i) students are asked to show a likely food chain for the moa. The correct direction of the arrows in a food chain is from the plant, to the herbivore, to the carnivore. The arrows show the direction of energy flow. This is an accepted scientific convention. Science has its own particular language and ways of expressing ideas. Food chains, with their arrows showing the transfer of energy to the consumer, are an example of this.

Nature of Science
Group discussion during the sorting exercise should provide insight into students' understandings about how scientists think and reason. It gives students opportunities to process and interpret information and to communicate scientific understandings. Look for evidence of students' understandings of the following nature of science ideas:

  • Scientists' observations are influenced by their science ideas
  • Scientists' predictions are based on their existing science knowledge
  • Scientists think critically about the results of their investigations
  • Scientific explanations may be in the form of a model
  • All science knowledge, in principle, is subject to change
  • Open-mindedness is important to the culture of science

The science matrices in the NZ Curriculum Exemplars could also be useful here to show development in "thinking in scientific ways".  

Next steps 
If this activity was completed as formative assessment it could then be easily adapted to either extend or further support students in their development of "thinking in scientific ways". For example students could be asked to research living ratites (the family of birds the moa is thought to have belonged to), identify shared characteristics and use these to make inferences about other behaviour of moa such as breeding patterns.
Students could find and evaluate evidence available to answer the question, "When did moa become extinct?"
Students could research evidence relating to other extinct animals, e.g., the dodo, and make inferences about their behaviour and appearance.

Some additional evidence and inference statements that may be useful to reinforce or extend learning have been included. In order to make inferences from these evidence statements many students will require additional background knowledge. This is provided on separate cards. Teachers could use this activity as an opportunity to reinforce the idea that scientists’ predictions are based on their existing science knowledge.

 

Evidence

Inference
Moa breastbones do not have ridges Moa could not fly.
Several living flightless birds such as the kiwi, ostrich and emu do not have ridges on their breastbones. The moa was a member of the ratite family of birds. It was likely to have behaved in ways similar to those of living ratites.
A large number of New Zealand trees have special adaptations to help protect them from browsing animals. Moa lived in New Zealand for a very long time.
Moa were single stomached animals. Moa did not live in big herds. They lived alone or in small groups.

Background knowledge

  • Breastbones of flying birds have ridges where the wing muscles attach.
  • The kiwi, ostrich and emu belong to a family called ratites.
  • It takes many generations for adaptations to evolve.
  • Single stomached herbivores need to eat a huge amount of food to get enough nutrients.

For a useful article about Moa, refer to: School Journal Part 2 Number 3 1982.