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Improving River Velocity Data Collection
As part of a physical geography investigation a group of students wanted to test the following hypothesis.
The velocity (speed) of a river increases downstream.
The students used three sites along a river, one kilometre (km) apart. At each site a ball was placed in the centre of the river and the time recorded for it to travel ten metres (m). This was repeated five times at each site.
Suggest one way that the data collection method could be improved.
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Marking points
- 1 Proposes one feasible change to how the river-velocity data are collected that could improve accuracy, reliability or coverage.
Full-mark answer
Use a flow meter instead of timing a floating ball, because it measures water velocity directly and reduces reaction-time and wind effects.
Why this answer loses marks
Collect the river data more quickly.
Speed alone does not improve accuracy, reliability or coverage; the answer needs a feasible methodological change and a clear data-quality benefit.