- where i collected the samples from. if i hadn't set out places on the grassy area and in the plant rich car park area, the test would not have been fair.
- i needed to also control where i got the water samples from. this is why i constantly had photos of maps, so i knew where i tested firstly so i could test around that area once again
- the thing i tried to change was when i got the samples and although this didn't make a huge difference in all aspects of the tests, it did affect the pollution level observations
Wednesday, May 13, 2009
variables in need of control
the variables that i needed to control to make this a fair investigation were:
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