Slaters

Slaters

Pencil and paperOnline interactive
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about using information about slaters to interpret the results of an experiment.
Read the information in the fact file and look at the diagram and notes about the experiment to answer the questions that follow.
The experiment
Some slaters were spread over a tray that had some wet soil and some dry soil. Half the tray was covered by a thick piece of cloth. After half an hour all the slaters were in the corner marked X.		 Slater fact file:
  • Slaters (also called woodlice) are crustaceans.
  • Crustaceans usually live in water, but slaters live on land.
  • Unlike insects, they have primitive lungs and an exoskeleton that is not watertight. Therefore they can easily lose water from their bodies.
  • When exposed to the sun they dry out quickly.
  • They prefer to have both sides of their body in contact with another surface. Often they will clump together.
  • They eat dead plant matter, including rotting wood.

Question 1Change answer

a)  What type of conditions did the experiment suggest that slaters prefer?

Question 1Change answer

b)  Use the fact file to give two reasons why the slaters might prefer to be in the corner marked X.
1.
2.

Question 1Change answer

c)  Name two places where slaters might live.
     Use the information in the fact file to give different reasons for each of your answers.
1.
2.
Task administration: 
This task can be completed with pencil and paper or online.
Copyright: 

Image source: Landcare research
Level:
5
Curriculum info: 
Science, Investigating in science, Living World
Keywords: 
behavioural adaptation, adaptation, habitats, slater, woodlice
Description of task: 
Task: Identify from an experiment the preferred living conditions of slaters, and use a fact file to suggest reasons why. Assessment focus: interpreting results of an investigation.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask 
 
Capabilitiy: Use evidence
This resource provides opportunities to discuss using data from an investigation to make inferences. 
Science capabilities: 
Use evidence
Answers/responses: 
  Y10 (09/2007)
a)

Wet/damp and dark

 moderate
b) For any 2 of:

  • They dry out quickly when exposed to the sun.
  • Their exoskeletons are not waterproof so they need to be away from the sun/in the dark so they don't dry out.
  • They prefer to have both sides of their body in contact with another surface.

2 correct – moderate
1 correct – easy
c) Any 2 reasonable places where it is damp and dark and where there is decaying vegetation, e.g. in leaf litter, under woodpiles, in damp buildings, under logs in the garden. Reasons given should link to conditions that are favourable to slaters. Do not accept:

  • "Because I have seen them there"
  • Non-specific environments, e.g. "In the forest"
  • Land/water/ damp place.)
 

2 plausible places + 2 plausible justifications – difficult
1 plausible place + 1 plausible justification – easy
Based on a representative sample of 294 Year 10 students in September, 2007.
Diagnostic and formative information: 
This task asks students to use evidence from two different sources, a diagram of an experiment and a fact file. It also asks students to synthesise evidence from the two sources.

  • A number of students did not refer to the evidence from the source mentioned in the question. For example for Question a) some students referred to the fact file rather than the experiment.
  • For Question a) many students described only one of the conditions shown by the experiment, i.e., either damp or dark.

Other interesting responses are shown in the table below.

  Response  Likely misconception
a)  Wet soil and under cloth Does not recognise that the investigation simulates conditions that slaters prefer, i.e., the cloth itself is not important, but the conditions it provides (darkness) is. (We accepted this as a correct answer, but this is a useful teaching point.)
  On the cloth  Interprets diagram very literally.
   Lower right hand side/ under the cloth  Describes where they gathered rather than the conditions.
c)  In cold places  Infers dark and damp places are cold.

 

Next steps: 
The investigation explores slater behaviour linked to minimising water loss. Clumping together reduces the amount of surface area exposed; therefore less water is lost from their bodies. Another resource that looks at this strategy, but to prevent heat loss, is Emperor penguins in Antarctica, which explores strategies Emperor penguins have for keeping warm.

Students who use only part of the evidence, or irrelevant or incorrect pieces of evidence, would benefit from practice in using evidence to justify their answers. For ideas go to the science capability Use evidence.

Nature of science

This resource could be useful for exploring the nature of science sub-strand Communicating in science and the key competency Using language, symbols, and text  by:
  • Comparing the two ways the information is presented (in a fact file and a diagram). What sorts of information are provided in each? What is the purpose of each piece of text? Why might a scientist choose these two ways of presenting the information?
  • Exploring the conventions used in the diagram. What does the cross show? What do the arrows show? What does the dotted line signify?
  • Discussing what the diagram does not tell the reader about the experiment (e.g., how many slaters were used for the experiment, how many times the experiment was repeated).

 

Emperor penguins in Anatarctica (a Level 5 resource) develops ideas about the strategy of huddling together.
Leaves for extreme climates is a Level 3 ARB resource that looks at strategies leaves have for survival, including water retention, and also asks students to provide evidence for their ideas.
 
The following Level 5 resources are a sample of those that ask students to use evidence to justify their answers:
Glaciers and global warming Students formulate questions about glaciers and climate change to show awareness that informed opinions are based on inter-related aspects of evidence rather than individual instances.
 
Skulls on the farm Students decide what sort of animals two skulls belong to. (This is a Level 3 task.)
 
For further ideas about activities for the science capability Use evidence, go to Use evidence.
 
Other ARB resources about using evidence: