:Balls
Trend Task
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Approach: One to one  Level: Year 4 and year 8
Focus:   Estimating weights
Resources: Pink foam ball, silver petanque ball, yellow tennis ball, orange cricket ball, recording book
280KB
Questions / instructions:

Here are four different balls. I want you to tell me how much you think each one would weigh.

Before you tell me, have a hold of each ball to get an idea of how heavy each one is.

Give the four balls to the student.

Now I want you to tell me how much you think each ball weighs. You need to tell me the unit of measurement, like grams or kilograms.

As each answer is given, write it on the recording sheet, ensuring that the units of measurement as given by the student are recorded.
   
% responses
2005 ('01)
Y4
Y8
1. How much do you think the pink foam ball weighs?
 
    Record student answer.    
    Accepted (actual =12g):
6 – 24g
9 (8)
23 (20)
 
< 6g
45
41
> 24g
32
29
any other response
14
7
    Unit given:
grams
54
84
 
any other response
46
16
2. How much do you think the yellow tennis ball weighs?    
    Record student answer.    
    Accepted (actual =58g):
29 – 116g
7 (6)
30 (22)
 
< 29g
51
38
>116g
34
27
any other response
8
5
    Unit given:
grams
54
82
 
any other response
46
18
3. How much do you think the orange cricket ball weighs?    
    Record student answer.
    Accepted (actual =164g):
82 – 328g
3 (3)
21 (13)
 
< 82g
49
39
> 328g
40
36
any other response
9
4
    Unit given:
grams
47
74
 
any other response
53
26
4. How much do you think the silver petanque ball weighs?    
    Record student answer.    
    Accepted (actual =726g):
363 – 1452g
15 (12)
34 (31)
 
< 363g
25
18
> 1452g or 1.452kg
51
41
any other response
10
6
   Unit given:
kilograms
61
60
 
grams
30
34
any other response
9
6
    Ball weights:      
weights in increasing sequence
75 (79)
92 (92)
any other response
25 (21)
8 (8)
Total score:
8–9
2 (2)
13 (11)
 
6–7
13 (13)
37 (31)
4–5
35 (36)
31 (39)
2–3
38 (39)
13 (15)
0–1
11 (10)
5 (3)

Commentary:
This was a difficult task for all students. Although progress was seen from year 4 to year 8, at most, one third of the students estimated the weight with much accuracy. Moderate improvement was seen in year 8 from 2001 to 2005.
 
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