New Zealand Science Teacher

A model for making NoS more explicit

15/04/2012

Carrying out school science investigations ‘like a scientist’: a model for making NoS more explicit, written by Rosemary Hipkins, NZCER.

“Learn about science as a knowledge system: the features of scientific knowledge and the processes by which it is developed; and learn about the ways in which the work of scientists interacts with society”. (Achievement aim for the Understanding about science sub-strand of the Nature of Science in NZC).

This paper presents one possibility for thinking about the ‘something more’ that key competencies could add to the “Understanding about Science” sub-strand of the curriculum, in particular as it intersects with the “Investigating in Science” sub-strand. It explains one simple but powerful way to help students learn something about the nature of science (NoS) that they can then “take away” as an outcome that has demonstrably strengthened their key competencies, and that teachers can manageably document as evidence of learning.

The basic idea is that students gain some powerful insights into science as “a way of explaining the world” (the words of this sub-strand at Levels 3 and 4) when they take an active part in investigations that are structured to model – so far as this is realistically possible– the types of activities that working scientists actually do. David Perkins would call this learning to play a junior version of the whole game of science (Perkins, 2009).

The idea described in this paper comes from an important synthesis made by two American science educators (Ford & Forman, 2006). These researchers put together existing insights from science education and another research field called science studies. Science studies’ researchers are social scientists (mainly sociologists and anthropologists) who study what scientists actually do, not what they say they do (which is more likely to be studied by philosophers). From their synthesis, Ford and Forman identified two main roles that every scientist plays as they work to build new knowledge, which is science’s main purpose in the world. These roles are: Role 1: Constructor of claims [about the natural and physical world]; Role 2: Critiquer of claims [made by other scientists]. They then described how teachers could reshape simple investigations so that students also experience these roles and the dynamic relationship that exists between them.

Two roles for being a scientist 

Science aims to create new knowledge about the natural and physical worlds, and to do so in ways that are convincing and carry authority. That is the very essence of its nature as a discipline. Scientists need to convince their peers in the first instance, and then others, that their new ideas should be adopted to either improve or replace what has gone before. They cannot do this just by the force of their personality or by cheating in some way. Some might try, but they ultimately get found out because there are ‘rules of the game’ that they need to follow if they hope to have their work elevated to the status of new knowledge. These rules will obviously be different in their specifics depending on the field of science involved (methods are different for a start) but Ford and Forman suggest that they can be reduced to the two main areas of activity named above: constructor of claims, and critiquer of claims. You cannot claim to be a scientist unless you can do both successfully and in combination.

The dynamic relationship 

Scientists work to make nature ‘speak’ in ways that they can then document. Simplifying situations to get rid of distracting complexities, manipulating the aspect of interest and then measuring and describing what happens are at the heart of the constructor role. Students are typically introduced to this part of investigating through experiences such as fair testing, perhaps later expanding this to learn about sampling techniques and so on. But this is only part of the real game of science as a knowledge-creating endeavour. New science claims won’t survive long unless they are convincing to a scientist’s peers. Other scientists who work in the same discipline area are in a position to be the most critical of audiences because they have the strongest inside knowledge. Critically probing the accounts of others for any flaws is at the heart of the critiquer role.

To ensure their claims will stand up to critique from their peers, scientists have to do several very important things. In the constructor role they must show how their ideas relate to what is already known in their field. Whether they accept or reject existing science theories of relevance to their work, they will not be taken seriously if they do not relate these theories to their argument. They also need to show how current theories relate to the ways they have manipulated the world to build their claim. This may sound obvious but it can be very challenging, especially when the aim is to get a theory replaced with a new one. If we want students to be able to claim that they are investigating like a scientist, then we need to find ways to help them play a junior version of this aspect of the whole game. Unless they do, they might come away from their investigation experiences with the mistaken belief that a seemingly convincing demonstration is, in and of itself, sufficient to confer scientific authority.

Second, in the constructor role the scientist must be clear and transparent in accounting for how and why they have manipulated their target aspect of the natural world. Their research questions, and investigation techniques, including measurement and data gathering strategies, must be able to withstand peer scrutiny. The argument they build around their findings must also be sufficiently clear to withstand scrutiny of its internal logic. The theory and the evidence must come together in a clear comprehensive report that follows expected conventions, including anticipating and discussing possible objections or alternative interpretations. As a report is being written or prepared for oral presentation, the constructor scientist keeps the critiquer in mind! When the shoe is on the other foot, and they are in the critiquer role, scientists will use their own deep knowledge to look for flaws or possible alternative explanations for the work of others.

Students are likely to learn some aspects of documenting and reporting as they take part in school science. For example, a paper in Issue 129 of the NZST (p.36) explains how students can be taught to clearly express relationships between sets of ideas by making deliberate and careful use of causal connectives in their written accounts of a phenomenon (Whitehead & Murray, 2012). However, students will not gain useful insights into the nature of science unless they are supported to see how new knowledge emerges from the interplay of both the constructor and critique roles. As individual or small group investigators they must carry out and build convincing accounts of their work. As part of the community of peers, they must learn how to take part in the more social and collective activities of critique. And they must be able to put these two types of experiences together in ways that help them to see how they are dynamically interrelated. You cannot get a sense of what it means to be a scientist unless you can play both roles.

Evidence of strengthening competencies

Ford and Forman note that assessment poses big challenges for more participatory views of learning. You can do the sort of participation described above, but you cannot take it away with you. By contrast assessment typically looks for evidence of what has been acquired, i.e. what you can take away. The model of dual-role investigations introduced in this paper addresses the assessment challenge by suggesting practical and specific possibilities for what might be documented as evidence of competency development. As they participate in mindfully carrying out and presenting their own investigations and/or explanations, and contribute thoughtfully and carefully to the critique of others’ investigations and/or explanations, students can show evidence that they are taking away dispositions and skills that matter for being a scientist. For example, a resource that the NZCER science team recently produced to help “unpack” the NoS strand of the curriculum provides some explicit suggestions of things that teachers could look for when students critique the ideas that others put forward (Bull, Joyce, Spiller, & Hipkins, 2010).

Critiquing others’ explanations

Do students ask questions for clarification? Are these directed at the person who proposed the idea? Are these questions about specific statements? Do students build on each other’s ideas? Do they make alternative suggestions? Do they ask why a student thinks something? Do they ask for evidence? Do they look for gaps in the explanations of others?

For other suggestions, see the NoS Kick Start, in particular page 4. (Bull et al., 2010) The next section of the paper draws on a recently posted Assessment Resource Bank (ARB) item (LW0652) developed at the intersection of Year 7–8 statistics and science to illustrate what tasks in this inter-disciplinary space could look. The investigation ideas have been taken from the responses of actual students who completed the task trials, but the classroom “action” is my reinvention. It is always our hope that teachers will take ARB items and creatively adapt them to their own classroom needs, as I have done here.

An example: Who grew the healthiest tomato plants?

Room 9 were moving into the final stages of a science/ statistical investigation that had begun late last year when, in small teams, the students planted and began to care for potted tomato plants. Over the summer break each plant had to be taken home by one volunteer from the team, and when they came back to school everyone could see that some plants appeared to be healthier than others, but also that there was variation in the overall combinations of ‘healthy’ features. The teacher challenged the groups to look at all the plants and then develop a set of measurement ‘rules’ for determining which group had the healthiest plant. She suggested they should try to think of at least four different measuring or counting rules, and then rank the plants by acting on their set of rules (the constructor of claims role).

Groups came up with a range of ideas for measuring and counting: number of leaves; size of leaves; colour of leaves; number of leaf buds; number of flowers; number of tomatoes; size of tomatoes; colour of tomatoes; height of plants; length of inter-nodes; bushiness of plants and so on. There was a lot of discussion about the relationships between some of these measures, and what to do when a specific measure showed considerable variability, for example, allowing for different leaf sizes on one plant. Next day, each group got busy measuring and counting according to their set of rules and recording the results on a table they had designed for this purpose. They then presented the results of their investigation to the class, explaining and justifying their measurement priorities and protocols as they did so. Other groups listened for indications that the rules and explanations had been similar to what a group of scientists might do when working together. They already knew about the critiquer role from an earlier science unit, and some of them had brought copies of the rubric they had developed earlier to get hints about what they might look for this time.

They listened for clear explanations of what would be measured or counted and exactly how this would be done so that the plant/plant comparisons were “fair”. (No one wanted their plant to be unfairly disadvantaged so this exercise engendered some very lively debate.) They also listened for explanations about why certain features might be regarded as stronger indications of health, and thought carefully about how groups had accounted for combinations of features.

One team put the height of the plants at the top of their list, arguing that healthy plants are tall plants. Other groups questioned this assumption, pointing out that the tallest plants were rather spindly and pale. Someone then noticed that this group’s height measurements did not match their own group’s record. However, when this was investigated further the critiquers were found to have made a measurement error, beginning measuring from the 1cm mark instead of zero. This aspect of their critique was not upheld (the teacher arbitrated when disputes needed to be settled). Yet another group observed that the plant with the most tomatoes was actually somewhat shorter than most of the others. They argued that this would have to be the healthiest plant because it could not have made so much fruit otherwise.

The debate lasted for some time and in the end the class agreed that no single indicator was a sufficient basis for a claim. However, despite a few ‘equal’ placings, they did come to agreement about which were the overall healthiest and least healthy plants. In the process they had debated many aspects of cause and effect in plant growth, and also come to a realisation that some qualitative indicators (green vs. yellow leaves) could not discriminate sufficiently well for the task at hand. At this point the teacher showed them how to construct a simple colour scale, using chips from paint colour charts. With three numbered shades of green and two of yellow the whole class then shared out the task of making an overall judgement about, and charting, every individual leaf, ready for their next mathematical challenge of calculating proportions of each colour per plant. Because this was a new measurement technique the teacher also displayed several examples of actual colour charts and the contexts in which they are used on the Smart Board. One example was the pH scale used for universal indicator, another was a colour scale used to help classify soil types (see for example: http://tinyurl.com/82q2sae). Some months later some students recalled this technique when confronted with the challenge of measuring different ways to slow down the browning of cut apples (see for example: here).

Conclusion 

If students learn to play both constructor and critiquer roles, even in the context of very simple investigations, they will have experienced what it means to do rigorous investigative work for which they will, and can, be accountable. As their ability to draw on science theories grows, so will the sophistication of the questions they can ask, the investigations they design, the justifications they can shape for the many choices they must make as they take part, and the explanations they shape. However, it would be very rare for school students to investigate a question for which science does not yet know the answer, unless of course they take a supporting part in an investigation shaped and led by working scientists.