Putting the Nature of Science strand into the water cycle

There is a large body of existing research literature on students’ understandings of evaporation and condensation, including the Learning in Science Project (LISP) at Waikato University (Osborne & Freyberg, 1985) and Science Processes and Concept Exploration (SPACE) in Britain (Russell & Watt, 1990). This was our starting point for further research to inform the development of the Assessment Resource Banks (ARBs) and other New Zealand Council for Educational Research (NZCER) resources. The NZCER research comprises four related fields of enquiry: • Systems thinking. This investigation was part of the ongoing research that informs the design of science resources for the ARB, and was based on some work by Assaraf and Orion (2005). The context was waterways. From this research, four stages of systems thinking were identified: identifying the parts of a system; identifying links between parts of a system without explaining the relationship; describing direct relationships; and describing multiple relationships that impact on each other (Bull, Joyce, & Hipkins, 2007a). This research provided a useful framework for considering students’ understandings of the water cycle, because this is also a system. • Students’ understandings about the water cycle. This was another investigation to inform ARB resources. A representative sample of 655 students from Years 4–10 from 17 New Zealand schools completed written items designed to find out their understandings about aspects of the water cycle (Bull, Hipkins, Joyce, & MacIntyre, 2007a). • Students’ representations of changes of state. Several resources trialled with students at Year 4 and Year 10 (again as part of the ARB research) were designed to investigate how students represented changes of state. Understanding how water is recycled and redistributed from place to place is important for sustaining the health of our planet. Developing solutions to issues such as global warming, climate change, water usage, growing more food, and protecting wildlife is dependent upon this understanding. The water cycle is, therefore, an important context for school science. However, to be able to use knowledge about the water cycle for making decisions, students need to understand that the water cycle is a complex and dynamic system in which multiple relationships impact on each other. Traditionally, the water cycle has been taught as a simple system. This is supported by the uncritical use of diagrams, the function of which is to simplify ideas. In fact, attempts to simplify may not only lead to misconceptions about the water cycle, but also do not encourage students to engage with the messiness of a complex system.