Chapter Graphic
 : Marbles in Water
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  Level: Year 4 and year 8
Approach: One to one
Focus: Account for the rise in water level in a container when an object or objects are added, in terms of water being displaced.
40k
Resources: 100ml jug, water,1 small marble, water, 2 large marbles.

Questions / instructions:
In this activity you are going to do an experiment with some water in a jug and some marbles. Give student equipment. Pour 80mls of water into the jug. Here's the jug. You can see that it has 80mls of water in it. Show student 80ml level mark.

     
% responses
y4
y8
1. What might happen to the water if you put one large marble into the jug?
water level would increase
83
95
Now put one large marble into the water.
    Watch what happens to the water.
a
a
2. Read the scale on the side of the jug.
    What is the level of the water on the scale now?
reads increase of about 15mls
83
83
3. Is there more, less or the same amount of water in the jug compared with before?
same amount
32
66
4. Why do you say that?
no water added or removed
(just displaced)
38
61
5. If you were to put one more large marble into the jug what would happen to the water?
increase by about 15ml
13
15
increase (unspecified)
80
82
6. What about the little marble?
    What do you think will happen when you put it into the water?
increase smaller amount
41
51
7. You can try it out. What do you notice?
not scored
a
a
8. What would happen if you took out all the marbles?
return to original level
90
89
go down
9
10
Commentary:
Both year 4 and year 8 students were generally able to predict the rises and falls in water level as marbles were added or removed. In question 3, year 8 students were much more aware that the amount of water did not change when marbles were added, but the results of question 8 suggest that year 4 students understood that removal of all objects would restore the original water level.
 
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