Chapter Graphic
: Rods
Trend Task
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  Level: Year 4 and year 8
Approach: One to one
Focus: Predict and investigate the heat conductivity of different materials, and explain practical applications.
56k
Resources: 5 rods, picture of saucepan, timer, mug, paper towel, water (boiling), electric jug

Questions / instructions:
In this activity you are going to find out and tell me about how quickly different materials let heat through them. Show student the rods as you name them.
 
% responses
y4
1999(1995)
y8
1999(1995)

1. Here are 5 rods.They are made of wood, perspex, copper, steel and aluminium.

I am going to put them into this cup then pour in boiling water. Then I will get you to touch the end of each rod to find out how much heat they are letting through.

 a a
2. But before we start, can you tell me which rod you think will let the heat move through most quickly? a a
  Prediction for first: a a
 
copper
10 (15)
28 (34)
aluminium
10 (11)
20 (22)
steel
15 (15)
21 (19)
perspex
28 (27)
14 (14)
wood
38 (32)
17 (11)
3. Why do you think that rod will let the heat through most quickly? a a
 
not marked
 a a

4. Now let's do the experiment. I am going to pour boiling water into the mug, and I want you to test each rod. When you test the rods, touch them like this:
Demonstrate how the rods should be touched — before the boiling water is added. Demonstrate use of timer.
I will get you to check them every 30 seconds, for two minutes.
With the rods already in the mug, pour boiling water into the mug, and get ready to time the 30 sec intervals. Repeat the following instruction 4 times (every 30 seconds).

 aa a
5. Feel each rod now, and tell me what you notice.
After 2 minutes of feel tests:		 a a
6. Now lift each rod out of the water and place them on the table in order, from the one that let the heat through most quickly, to the one that let it through least quickly. Be careful to lift them out with a paper towel so that you don't burn your fingers.
a
a
  Observations:
a
a
 
copper first
80 (90)
86 (89)
aluminium second
71 (79)
77 (83)
steel third
81 (81)
84 (86)
perspex fourth
65 (61)
70 (67)
wood fifth
68 (61)
71 (69)
7. Materials that let the heat travel through easily are called good conductors. Which rods were good conductors of heat?
a
a
 
copper
92 (95)
97 (97)
aluminium
87 (87)
93 (93)
steel
54 (52)
49 (37)
8. When toffee is made, the ingredients are made very hot, a lot hotter than water. If we had spoons made out of each of these materials, which spoon would be the best for stirring the very hot toffee mixture?
a
a
 
wood and/or perspex
4 (3)
3 (7)
wood
41 (35)
58 (56)
perspex
14 (16)
12 (11)
copper
26 (27)
15 (11)
9. Why would you use that material?
a
a
 
not good conductor of heat
56 (60)
69 (85)
Show student the picture of a saucepan.
The saucepan in this picture is made of stainless steel.It has a copper bottom, and a plastic handle.
a
a
10. Why do you think it has a copper bottom?
a
a
 
conducts heat well
75 (70)
91 (93)
11. Why do you think it has a plastic handle?
a
a
 
conducts heat poorly
91 (92)
96 (95)
Commentary:
Both year 4 and year 8 students conducted and interpreted the experiment quite well. Year 8 students showed better initial knowledge of the rod materials, and were better able to explain the practical applications. There was no marked change in performance between 1995 and 1999.
 
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