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Critical thinking about advertising claims

Focus key competencies: Thinking (evidence-based); managing self

Learning area context: Sciences


In their very first lesson, students in this year 11 science class looked at an advertisement for 'healthy chocolate'. The teacher asked them to discuss whether or not they trusted the claims made in this advertisement. They were encouraged to justify their decisions and record their thoughts on whiteboards, post-its, or electronic forums.

Next the teacher gave the students some ‘evidence’ behind the claim. They had to sort and interpret this for themselves, and then revisit the advertisement to consider their original decision. Had it changed or stayed the same? Why or why not?

A follow-on series of group activities was designed to help students develop their understanding of what makes science trustworthy (or not). The teacher gave them a framework from which they could build a checklist of things to look for in trustworthy science. They then applied this checklist to a range of case studies to evaluate the science behind claims. Once they had some confidence with the checklist, the teacher gave them an article outlining the science behind the claim 'healthy heart chocolate' and asked them to evaluate this article using their checklist. Once they had done this, students revisited their decision about whether or not to trust the advertisement.

At no time did the teacher say what she thought. Nor did she indicate that a particular answer was right or wrong. She simply asked students to justify their ideas, with increasing amounts of evidence as they worked through the tasks. She has found that this sequence of activities generates high levels of engagement in science: students see their ideas as valued, and they develop confidence in their own ability to evaluate and recognise the imitations of some scientific claims.

The checklist that students developed during this activity continued to be used as they developed their own investigations later in the year. The teacher continued to challenge them to explain why she should trust their conclusions, using the language developed for the checklist. In subsequent NCEA assessments of students’ own investigations, the majority of year 11 students were able to develop valid methods and evaluate their methods with specific reference to ideas within the checklist.

In the following year the teacher observed these same students vigorously debating the methods they had devised for investigations. They were confident in their understanding of the nature of science investigations*, and able to express and justify their opinions and reflect on their methodology. (*Science educators emphasise that NOS insights do not develop just by “doing” practical investigations: what is being modeled here is an explicit focus on the nature of investigative activities that claim to be building robust and defensible knowledge claims - see, for example. Lederman, 2007.) This was evidence of the success of her plan that year 12 and 13 students who go on in science have opportunities for the ideas in the checklist to be reinforced and further developed as they design and evaluate more complex investigations. Students in this teacher’s senior science classes are encouraged to self-assess and peer-assess the different stages of their own investigative work using the checklist and their deepening understanding of the nature of science.

Reciprocal relationships between the subject and the key competencies

The NZC learning area statement says that when studying science students “use scientific knowledge and skills to make informed decisions about the communication, application and implications of science as these relate to their own lives” (p. 28). They also learn that science “involves particular processes and ways for developing and organising knowledge” (p. 28). These two ideas (citizenship skills and knowledge/ scientific ways making knowledge claims) come together in the Communicating in Science sub-strand of the Nature of Science strand of NZC. At level 6, one of the achievement objectives for this sub-strand says that students will “apply their understandings of science to evaluate both popular and scientific texts including visual and numerical literacy”.

In science, strengthening thinking competencies can include opportunities for critical evaluation of evidence that supports a claim. Science is evidence-based but evidence can also be open to interpretation, depending on the frame of reference employed. As they work through a carefully structured learning sequence, students learn about the sorts of questions to ask to test evidence against claims that purport to be ‘scientific’. In this way, they are supported to ‘think scientifically’ themselves, and they practice justifying their ideas based on the evidence they have.

Within the context of exploring claims in advertisements students also have opportunities to develop their self management competencies. When they are asked for their opinions and ideas, and there is no one right answer to be second-guessed, students see that their ideas are valued. Such open-ended experiences can support them to see themselves as capable learners in science. This unit is well-timed, coming as it does at the very start of year 11.

Reflections on effective pedagogy

The key difference between this and more traditional approaches to science is that students are asked for their ideas, which they revisit and refine as they are exposed to more evidence and develop an understanding of factors that make scientific research trustworthy. (Some nature of science researchers say that the most valuable contribution this aspect of the curriculum makes to students’ education for future citizenship resides in fostering this sense of who to trust, when and why - see, for example, Allchin, 2011.) Their ideas are valued, and effective questioning and discussion is used to explore and extend their own thinking. There is no one right answer regarding whether or not to trust the claim made in the advertisement, but students are given feedback on how well they justify their ideas/opinions. All of these features have been carefully designed to foster initiative and build for each student the sense that they are able to reason in science-like ways, even if they have not previously had opportunities to do this.

The unit of work provided students with challenge through the use of:

  • Ÿseeking justified opinions; not accepting the claims of others at face value
  • Ÿuse of a context that had no 'one right answer'
  • Ÿsubsequent application of the ideas to create students’ own investigations.

One challenge for teachers is to continue to select contexts that allow more than one answer to be substantiated. This teacher’s students carried out an investigation later in the year in which they explored how i-pods may affect hearing. The complexity of this issue and its relevance to their lives engaged and challenged the students to further practice justifying their ideas based on evidence and evaluation of scientific methods.

Discussion starters: Links to lifelong learning

In this story some students’ competencies in managing self are challenged by finding themselves in a context where there is not one self-evidently right answer. They cannot second-guess or “just know” what the teacher wants to hear. How might such experiences build resilience as a learner and how important do you think it is to do this, especially with “lifelong learning” in mind?

In what sense might evidence-based thinking be considered to be an example of “higher order” thinking? One set of criteria for designing learning tasks that invite higher order thinking was provided in the story Sustainable food preparation. How does the learning action described in the current story stack up when evaluated against those criteria? How might experiences of being an evidence-based thinker support and encourage ongoing learning success?

Looking across all the stories, what connections do you now see between the key competencies and the NZC vision that all students should become “confident, connected, actively involved lifelong learners”?


Allchin, D. (2011). Evaluating knowledge of the nature of (whole) science. Science Education, 95, 518–542.

Lederman, N. (2007). Nature of Science: past, present, and future. In S. Abell & N. Lederman (Eds.), Handbook of research on science education. Mahwah, NJ.: Lawrence Erlbaum Associates.

Published on: 15 Apr 2014