What makes a reptile a reptile?

This task is about using evidence to decide whether an animal is a reptile or not.

Scientists divide living things into different groups.
The list below shows some of the features they use to decide if an animal belongs to the group called reptiles.

Features of reptiles

They have a backbone.
They are cold-blooded.
They breathe with lungs.
They have dry skin covered with scales. Some also have a hard shell.
They have ear holes but no ears.
They have 4 legs or no legs.
They lay eggs which have a strong, soft shell. A few reptiles have live babies.

a) Use the information from the list to decide whether each of the following animals is a reptile. Give reasons for your decisions.

Question

i) Is this a reptile?

- Yes
- No
- Can't tell

Reason your answer.

Question

ii) Is this a reptile?

- Yes
- No
- Can't tell

Reason for your answer.

Question

iii) Is this a reptile?

- Yes
- No
- Can;t tell

Reason for your answer.

Question

iv) Is this a reptile?

- Yes
- No
- Can't tell

Reason for your answer.

Question

v) Is this a reptile?

- Yes
- No
- Can't tell

Reason for your answer.

Question

vi) Is this a reptile?

- Yes
- No
- Can't tell

Reason for your answer.

Question

vii) Is this a reptile?

- Yes
- No
- Can't tell

Reason for your answer.

Task administration:

This task can be completed with pencil and paper or online (with SOME auto marking).

Background information

This task comprises an Understanding about science idea, science classification, within the context of reptiles. The key ideas that are covered in the task are shown in the table below.

Nature of science idea

Science knowledge and skills

Understanding about science

•	Scientists have agreed on a system for classifying living things.

Scientific classification of animals

•	There are many ways of grouping living things. Using a science classification is one way.
•	Reptiles are one class of animals within the scientific classification system.
•	Some features of animals are easily observable, but others are not.

Over time, the understanding of the relationships between living things has changed, and this has led to revisions in how scientists classify animals and plants. Originally scientific classification was based on the observable structural similarities of different organisms. Now scientists are able to use a wider range of evidence including DNA from both living organisms and fossils. Today's scientific classification system combines using observable physical features and the evolutionary relationships between plants and animals.

This activity focuses on the observable physical characteristics of animals for two reasons.

•	Students who do not have prior knowledge about the animals can still successfully complete the task.
•	Close observation skills are important to develop in science because it is one way to gather evidence.

However, many students will also draw on their prior knowledge, both of scientific classification and of features of animals that cannot be observed from a photograph.

Image source: Wikipedia

Image source: Virtual Colombia

Image source: Wikipedia

Image source: Virtual Australia

Image source: George Pope (NZCER)

Image source: Wikipedia

Image source: DOC

Answers/responses:

Y6 (06/2009)

Y8 (06/2009)

Snake - Yes; or
I can't tell (3 responses Y6/ 3 responses Y8).
Supporting reasons
Identified all 7 features of reptiles given;
or
Identified features observable from photograph (scales, no legs) †

very easy

very difficult

‡ see note

very easy

very difficult

‡ see note

ii)

Fish - No; or
I can't tell (14 responses Y6/ 3 responses Y8). *
Supporting reasons: any of

•	They do not breathe with lungs
•	They do not have dry skin

[Neither feature is observable from the photograph, although some students may recognise gill covers.] †

easy

‡ see note

easy

‡ see note

iii)

Frog - No
Supporting reasons: any of:

•	They do not have scales or a shell (observable from photograph).
•	They do not have dry skin (not observable from photograph).

difficult
‡ see note

iv)

Lizard - Yes; or
I can't tell: (5 responses Y6/ 6 responses Y8) *
Supporting reasons:
Identified all 7 features of reptiles given
or
Identified features observable in photograph (scales, 4 legs - some students may also make a link between the tail and a backbone.) †

very easy

very difficult

‡ see note

very easy

very difficult

‡ see note

Bird - No
Supporting reasons: any of

•	They don't have scales/ they have feathers (observable from photograph)
•	They have two legs (observable from photograph).
•	They are not cold-blooded (not observable from photograph)

very easy
‡ see note

vi)

Turtle - Yes; or
I can't tell: (15 responses Y6/ 19 responses Y8). *
Supporting reasons:
Identified all 7 features of reptiles given
or
Identified features observable from photograph (scales, shell). †

very easy

very difficult

‡ see note

very easy

very difficult

‡ see note

vii)

Weta - No
Supporting reasons: any of

•	They have 6 legs (observable from photograph)
•	They don't have scales (observable from photograph)
	They don't have a backbone (not observable from photograph)
•	They don't have lungs (not observable from photograph)

easy
‡ see note

Question B
Responses that indicate the student is aware of issues of consistency between scientists
and/or
Answers that indicate that the student is aware of issues of communication.

very difficult

Based on a representative sample of 169 Year 6 and 171 Year 8 students

NOTES:
* Because very few students used the I can't tell option, the number of students who did so is reported.
† If students are only using observable features to complete this task, the most appropriate answer for Questions a) i), ii), iv) and vi) is I can't tell.
‡ Refer to Working with students,diagnostic information about Classifying

Diagnostic and formative information:

Diagnostic and formative information
Question b) probed students' understanding of the purposes of having a classification system. Few students answered this question adequately (or at all). However, one class did substantially better than the others, suggesting that they may have collectively been involved in some experience that helped them come to some understanding of this nature of science idea.

Some examples of acceptable responses were:

•	So you have got more chance of figuring out what animal it was (Year 6)
•	Because grouping them gives info on the animal so it's easier to research the animal (Year 8)
•	They send their results to other scientists or the other scientists do tests and research and get the same answer. (Year 8)

Next steps
Use Question b) as the basis for group and/or class discussion while working on classification.

Other discussion starters could be:

•	What could happen if scientists in different countries had different ways of grouping living things?
•	Provide a description of a fictional "newly discovered" animal. Ask students: How could we work out which group of animals it belongs to? What do you think scientists do when a new species is discovered?

Read and discuss real-life stories of scientists using or developing scientific classification (go to Other resources).

Classifying

Diagnostic and formative information
Students used a range of strategies to carry out Question a)

•	Some students used the table of features of reptiles to identify and justify whether the animals were reptiles or not.
		This animal cannot be a reptile because it has feathers and two legs. (Year 8)
•	Some students used the table to identify which animals had these features, but also drew on their prior knowledge.
		I know a weta is an insect. It has 6 legs, no scales, no hard shell, doesn't have a backbone. (Year 6)
•	Others justified their answers without reference to the table or the features of the animals, i.e., they used their prior knowledge of classification.
		From what I have learnt at school I've learnt frogs are amphibians.(Year 6) Because it's an insect. (Year 8) I just know it's an amphibian.(Year 6)

Providing evidence for responses
To classify an animal as a reptile all the features of reptiles need to be present.
Very few students gave all seven of the features provided to justify their classification as a reptile. Because not all of these features are observable, students who did so would need to be calling on their prior knowledge of the animal.
Mostly, students justified their response by identifying only one or two features.

They breathe through their lungs. (Year 6)
They have a hard shell and lay eggs. (Year 8)

A number of students gave generalised responses that, while technically correct, did not specifically reference back to evidence.

It has all of the features of a reptile.(Year 6)

It is possible that some students may have just listed all the features rather than really thinking about the criteria.

Only one feature needs to be identified to exclude an animal from the reptile group, however.

Because it breathes in water through its gills. (Year 6)

Many students, though, did provide multiple reasons why an animal is not a reptile. This seemed to be easier for some students than giving all the reasons why an animal is a reptile.

Because it's an insect. It doesn't have a backbone and has no lungs. (Year 6)

The "I can't tell" option was provided because not all features of reptiles are obvious from a photograph. Using evidence to justify decisions is an important aspect of science, and providing this option helps to identify whether students understand this. Not many students used this option (refer to Marking student responses), and when they did hardly any gave a reason why they couldn't tell, except in some cases to say that they didn't know the answer. Few showed that they recognised that it is legitimate to suspend making a decision if there is insufficient evidence. The following is an example of a student who was able to justify her "I can't tell" choice.

I can't tell if it has a dry skin. (Year 6)

The most difficult animal to classify was the frog. This is not surprising because frogs share many features of reptiles. Students either had to recognise that it has damp skin (not obvious from a photograph), or know that it is an amphibian.

Features most commonly used to exclude other animals were:

Animal	Features
Fish	lungs/gills
Heron	feathers and number of legs Many students also identified the fact that it is warm blooded. Of all the animals, students were most likely to give multiple reasons for excluding this one.
Weta	number of legs

Understanding the concept of scientific classification
A few students clearly showed that they understood that some features of animals are common to more than one class.

Fish have backbones, are cold-blooded, don't breathe through their lungs though (Year 6)
(A bird has) feathers, 2 legs, and has a beak – but has holes to hear and lays eggs (Year 8)

Next steps
Choose from the suggested activities below to address learning needs of your students.

Encourage students to justify their classifications.

Provide students with opportunities to practise using more than one piece of evidence to justify their groupings.

Promote using the "I can't tell" option when there is not enough evidence to make a decision.

As a class or in groups get students to debate their decisions. Explore further those animals that students are not sure about, or cannot tell.

To focus on the importance of observation as one of the skills used to classify animals, discuss which features were not used from the list, and give reasons why these were not used, for example:

Because it's impossible to see or feel these aspects of the animals (Year 8)

Some students may also talk about being able to use prior knowledge even if the features are not visible. For example, they may know that a weta is cold-blooded. More advanced students may be ready to also discuss the limitations of just using observation to classify animals scientifically. Refer to Task administration, background information.

Challenge students who "know" which group an animal belongs to, to provide evidence for their decisions.

The following ARB resources encourage students to classify animals by using evidence. They also help students to reach the understanding that all features of a group have to be present for an animal to be classified as belonging to that group. They can be used as group activities to encourage debate, or individually.

Misconceptions

Diagnostic and formative information
Students' responses uncovered some misconceptions about animals and their classifications. Two of the more common were:

Confusion about features of some classes of animals
This may in some cases be related to a misconception that mammals equate to animals.
Examples of response

Only mammals have feathers. (Year 6)
Because fish are mammals and mammals are warm blooded and they breathe with gills (Year 8)

Next steps
If appropriate check that students understand the science meaning of animal, as opposed to its everyday usage.

Revisit or introduce features of other groups of animals, especially when a specific misconception about a group is suspected. Provide clear photographs or diagrams of a set of animals and get students to decide whether they belong to the described group. Justify their decisions. Some ARB resources may be suitable.

Confusion about features of some animals
Examples of response

Because it (weta) has 6 legs not 4 or none and it is warm blooded (Year 8)
Because (a snake) doesn't have a backbone (Year 8)
No, because (a weta) does not lay eggs (Year 8)
Because fish, well most, are warm blooded (Year 8)
(Weta) breathe with lungs. (Year 6)

Next steps
Encourage students to check their ideas.

•	How do you know (that a weta/shark/ is warm-blooded/ has a backbone/ breathes through lungs/ etc.)?
•	How can you check your ideas?
•	Are there any clues from looking at the animal carefully?
•	How can you check your ideas if you cannot see the feature?

Key competency – Thinking

Diagnostic and formative information
Question a) requires students to synthesise quite a lot of information and apply it to specific examples. Some students clearly struggled with this. For example, some applied the given information incorrectly: they may have, for instance, said a fish is not a reptile because it is cold-blooded (cold bloodedness was given as a feature of reptiles).

Using multiple pieces of evidence involves complex thinking.

Next steps
Provide or help students to develop a graphic organiser that supports students to process multiple pieces of information. Some ARBs provide more support in processing complex information by getting students to tick off individual features before they decide whether the animal fits a particular group. This strategy also helps students to understand that all the features of that group need to apply. The following ARB resources may be useful models to adapt:

Cards that they can physically move help some students. Each feature of a reptile could be presented on separate cards, and the appropriate ones placed under the animal. An "I don't know" pile will help students identify which features they cannot observe.

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What makes a reptile a reptile?

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