This can be done by brainstorming a list of words that students associate with catchments. It might be necessary to assist by contributing some words as prompts. Working in small groups, students could write the words on separate slips of paper, then either group the terms under headings or develop a concept map. A group spokesperson could then explain the group's reasoning to the teacher. Students may think that the word 'catchment' means a dam or water storage facility.
Some students associate the word 'pollution' only with industrial chemical pollution.
Excessive amounts of nitrates and phosphates in a waterway may not be perceived as constituting a pollution problem because these nutrients have a natural origin. The activities 'The story of a river' and 'Good versus poor catchment management' reinforce the idea that there is a wide range of pollutants. Students can mistake turbid water for polluted water. A sample of the water can be placed in a jar and allowed to stand in the classroom for a few days to show students that the turbidity gradually clears. The waterbug sampling activity in 'Assessing your waterway' enables them to classify the health of a waterway using the types of waterbugs present.