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Approach: One to one Level: Year 4 and year 8
Focus: Friction
Resources: Wooden board, long rubber band, wooden block
352Kb
Questions/instructions:  


Preparation: Stretch the rubber band between the two wooden anchors on the wooden board. Show the student the wooden block.

If you turn the wooden block over you will see that there are three different materials glued to three sides of it. It has sides that are wood, plastic, flannel and sandpaper.

Show wooden block.

I’ll show you how this works with the wood touching the board. [Click on graphic to enlarge.]

Demonstrate the wooden block sliding along the board with the wood touching the board. Put the wooden side face down and next to the rubber band. Lift the rubber band so that it sits on top of the peg then pull the block back to the line. Let it go.
 
% responses
2007 ('03)
y4
y8
1. Which side touching the board do you think will make the block slide further?
    
 
plastic
77 (75)
82 (87)
wood
5 (6)
5 (7)
flannel
14 (18)
12 (6)
sandpaper
3 (0)
0 (0)
2. Why do you think that?
 
less “friction”
0 (2)
4 (9)
smooth, slippery, less catching/ rubbing/grippy
74 (79)
84 (81)
3. Which one of the four sides do you think will prevent the block from sliding as far?
 
plastic
2 (5)
1 (0)
wood
4 (1)
1 (1)
flannel
17 (6)
9 (8)
sandpaper
77 (86)
89 (90)
4. Why do you think that?
 
more “friction”
0 (0)
5 (12)
rough, more catching/rubbing/grippy
58 (70)
80 (78)
Now you can test out your ideas. Put the side you are testing face down and next to the rubber band. Lift the rubber band so it sits on top of the peg and pull the block back to the line. Then let it go.
If necessary help the student set up the block.

5. What did you find out?
prompt: Explain why that happened.
Tested all sufaces:
yes (without prompting)
12 (15)
19 (30)
yes (with prompting)
51 (53)
55 (50)
no
37 (32)
26 (20)
Reported:
sandpaper least distance
53 (58)
61 (56)
For slide furthest, reported:
plastic
78 (78)
85 (85)
wood
6 (5)
3 (6)
flannel
1 (2)
2 (2)
Quality of explanation:
very good (“friction”)
0 (0)
8 (9)
good (smooth plus)
2 (4)
7 (5)
fair (smooth vs. rough)
51 (58)
61 (57)
poor/missing
47 (38)
24 (29)

Total score:
4–6
35 (49)
66 (68)
3
31 (24)
18 (23)
2
23 (17)
13 (8)
0–1
11 (10)
3 (1)
Subgroup Analysis [Click on charts to enlarge] :
Year 4
Year 8
Commentary:
The performance of the apparatus for this popular task was a little erratic, so that the anticipated results were not always observed. The total score focused on prediction and explanation, rather than experimental findings. There was a moderate decline in the performance of year 4 students between 2003 and 2007. Mäori students performed similarly to Pakeha students.