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Disinfecting wastewater interactive Capability: Critique evidence NoS achievement aims: Investigating in science Contextual strands: Physical world Level : 5

Science Learning Hub

This interactive resource from the Science Learning Hub provides an opportunity for students to strengthen their capability to critique evidence in the context of science.

Curriculum Aims and AOs

The Nature of Science strand


Achievement objectives relevant to this resource

Investigating in science

Carry out scientific investigations using a variety of approaches: classifying and identifying; pattern seeking; exploring, investigating models, fair testing and making things or developing systems


Show an increasing awareness of the complexity of working scientifically, including recognition of multiple variables.

Living World


Achievement objectives relevant to this resource

Using physics

Apply their understanding of physics to various applications


Explore a technological or biological application of physics

Learning focus of this resource

Students critique the basis on which they make decisions when using a Science Learning Hub interactive.

Learning activity

This interactive resource models the complexity of maintenance decisions that have to be made on a daily basis to keep a waste water plant operating at optimal conditions. UV light is used to kill microbes in the water before discharge. The object of the exercise is to keep UV levels high without incurring excessive maintenance costs. Doing this requires students to notice and respond to four separate data inputs. The significance of each these inputs is conveyed by a short video clip that they watch at the beginning of the interactive. However students need to “connect the dots” between the video and the model to determine the significance and impact of each variable once confronted with the actual scenarios. 

Adapting the resource

Once students have interacted with each scenario, discuss what they needed to know and notice in order to make correct decisions:

  • Could they afford to ignore any of the four variables? Why or why not?
  • How did they decide what each piece of data was actually telling them about the present situation?

Ask for their ideas about how the maintenance engineers would have come up with this set of operating protocols. [As the video shows, deep practical experience has been built into the process of determining what evidence to collect, across what range of data points.]

If scientists came up with new and better UV tubes, what might the engineers need to do to reset the maintenance instructions? [Everything would need to be recalibrated and new maintenance routines developed.]

Could you safely work as a maintenance engineer at this plant without being able to critique the data streams? Why or why not? [Following instructions by rote only works as long as all data stays within the set parameters. If data for any variable moves beyond these set limits, you need to understand why the data is important in order to make a critical decision about what to do next.]   

What’s important here?

Citizens are often called on to make evidence-based decisions, including in work contexts, and appropriate decisions often require the integration of evidence from multiple sources. Critical thinking is needed to determine the meaning of data and what any unexpected shift might be evidence of. Failure to perceive significance in data shifts can be a cause of serious mishaps or accidents.

Developing an appreciation for how evidence in science is generated supports students to become scientifically literate, i.e., to participate as critical, informed, and responsible citizens in a society in which science plays a significant role. (This is the purpose of science in NZC.)

What are we looking for?

Can students read meaning into the data presented to make correct decisions?

Can they critique the basis on which these maintenance decisions are made?

Can they discuss how and why adjustments might need to be made so that decisions remain valid?  

Opportunities to learn at different curriculum levels

For suggestions about adapting tasks in ways that allow students to show progress in critiquing evidence see Progressions .

Exploring further

The science content is limited in this resource. However, this activity could be a context for introducing UV as part of the electromagnetic spectrum that humans harness for technological applications. To develop understandings about the Physical World, teachers would need to provide opportunities for content learning as well.

Alternatively it could be embedded in a unit of work about the water cycle, or water treatment, in a Material World context.

Other resources for this capability

Key words

Science learning hub, UV light, water treatment