How well does a "green" fridge work?

How well does a "green" fridge work?

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
How to do this task:

  • Soak a terracotta pot in water overnight.
  • Next day, place a container of juice in the tray, e.g., yoghurt container. Place the terracotta pot over this and block the hole at the top with plasticene. Next half-fill the tray with tap water.
  • Once set-up as illustrated, place this and another yoghurt container of juice in a sunny place outside.
a)
Record the temperature of the juice in both containers of juice every 3 minutes for the next 30 minutes. (Remove the plasticene to do this).  
 
Time (min) Temperature of juice under terracotta pot (°C) Temperature of juice outside (°C)
0    
3    
6    
9    
12    
15    
18    
21    
24    
27    
30    
 
 
 
b)
Write a summary of what your results show.  
 
 

    

 

    

 

  
c)
Explain how your "fridge" works.  
 
 

    

 

    

 

  
d)
Who might find this "type of fridge" useful?  
 
 

    

 

    

 

  
e)
Parts of this investigation may not be considered to be a "fair test".
Explain one way this investigation may not meet the requirements of being a "fair test".  
 
 

    

 

     

 
Task administration: 
[Equipment: Terracotta pot; thermometer; 2 similar containers for juice, e.g., yoghurt containers; plasticene; tray; juice; sunny day.]

  • In trialling we used a starting temperature of 10°C, and then measured the temperature every 3 minutes. These were the results we obtained:

 

Level:
5
Curriculum info: 
Science, Investigating in science, Physical World
Keywords: 
physical inquiry, insulation, fair testing
Description of task: 
This practical task requires students to follow instructions for making a 'green fridge' to determine its efficiency. Students collect and record data from their investigation and answer questions.
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:
  • methodologies for fair testing and data tables
  • making meaning from data.
 
Science capabilities: 
Gather and interpret data
Answers/responses: 

a)

Table is completed.

b)

A summary which reflects the results in the table.

c)

The inside of the terracotta pot stays cooler because the heat is used to evaporate the water.

d)

People who live in warmer areas without electricity/campers in the bush.

e)

Any 1 of:

  • The juice outside is not sitting in water.
  • There are different colour surfaces involved, e.g., brown of terracotta vs. white of yoghurt container, etc.

 Extension: graph results.