A group of students were collecting data along a river channel as part of an investigation into changes in river characteristics downstream.
The students had planned to measure the surface velocity of the river using a floating tennis ball and a stopwatch, but a strong wind was blowing directly upstream, pushing the ball backwards.
State one way they could adapt their technique to improve the accuracy of their velocity measurements.
125 exam-style questions on Edexcel A GCSE Geography Investigating physical environments (rivers or coasts). Each one has a worked solution and a mark scheme showing where the marks go.