Esther F.
de Waard
*,
Gjalt T.
Prins
and
Wouter R.
van Joolingen
Faculty of Science, Utrecht University Freudenthal Institute for Science and Mathematics Education, The Netherlands. E-mail: e.f.dewaard@uu.nl
First published on 11th April 2020
Sustainability has become a prominent theme in society and can be considered as an integral part of scientific citizenship. This study investigates to what extent the production, use and re-use of (bio)plastics initiates students’ reasoning and to identify the kind of content knowledge students put forward. The structure of students’ arguments was mapped according to Toulmin's model of argumentation, i.e., claim, data, warrant & backing and qualifier & rebuttals. Students (N = 27, grade 10 & 11) participated in groups of three. The students were introduced to the topic of the production, use and re-use of plastics by watching a video, answering questions, reading articles and having interviews and group discussions. Students were prompted to argue on the sustainability of bioplastics and fossil-based plastics. The results show that students frequently used arguments related to preventing pollution, designing to recycle and designing to degrade. However, themes such as avoiding waste, origin of energy and materials, energy efficiency and costs were rarely used or even absent in students’ reasoning. Overall, the students’ reasoning contained all of Toulmin's categories, and especially the increase in the number of qualifier & rebuttals is interpreted as an indication of awareness of the complexity of the issue at hand. This study underlines that students are able to bring in relevant scientific knowledge when confronted with a suitable sustainability issue, but also more societally oriented arguments enriched their perspective. Implications for the design of interventions aiming to engage students in life cycle analysis (on plastics) are discussed.
In higher education, a relatively large amount of attention goes to ESD, and some well-documented examples are available (Galgano et al., 2012; Ribeiro and MacHado, 2013; Mälkki and Alanne, 2017). The examples show the intention to incorporate sustainability, with relevant scientific knowledge and skills, into curricula. However, in contrast to higher education, current secondary chemistry curricula and chemistry textbooks do not provide sufficient opportunities for students to become engaged in sustainability issues and dilemmas (Eilks, 2015; de Goes et al., 2018). This might be partly due to the fact that (most) sustainability issues are ill defined, with no single, straightforward solution(s) that works always and everywhere, and involves various stakeholders with (sometimes) conflicting ideas. Sustainability issues might be regarded as so-called socio-scientific issues (SSI), which are (also) defined as rather open-ended problems that do not have an one-dimensional (i.e., politics, economics or ethics), clear solution (Sadler, 2011). Several studies have reported that using SSIs as contexts increases students’ interest in science learning, creates ethical awareness and prepares students for participation in society (Juntunen and Aksela, 2014), in line with the goals of ESD. However, which sustainability issues are suitable for ESD in chemistry education? It is not trivial to develop high quality teaching materials, incorporating innovative pedagogies, that enable students to study complex sustainability issues in which multiple dimensions must be dealt with at the same time (Hofman, 2015). Burmeister and Eilks (2012) have shown that plastics are a suitable topic for ESD in chemistry education. In this study, we investigate to what extent the production, use and re-use of (bio)plastics forms a suitable context to initiate students’ life cycle reasoning and to engage them in arguing on a well-known sustainability issue in the domain of chemistry.
After the introduction of sustainability and the guidelines for sustainability, there was a demand for tools to quantify the sustainability of a specific process or product. When the concept of sustainability was introduced, there were companies that tried to find methods to, for example, compare different products with each other on environmental impact. Aspects such as energy efficiency, pollution control and waste products were analysed in those comparisons. In the 1990s, scientific influence on such comparisons resulted in normalized methods to analyse the whole life cycle of a product (Guinée et al., 2011), i.e., life cycle assessment (LCA) to evaluate the environmental burden of a product, process or activity. LCA consists of four steps. In step 1, the goal and scope definition are set. In step 2, an inventory analysis of extractions and emissions is done. In this step, the complete picture, e.g., “use of raw materials and energy,” “emission of pollutants” and “waste streams” is obtained. Step 3 is focussed on impact assessment, i.e., classification of environmental impacts and an evaluation of which ones are important for the business at hand. Step 4 is an interpretation phase, in which a check is made on the conclusions. In short, LCA is a tool to monitor the flows of materials and energy for the whole life cycle, input and output, in quantitative measures. A life cycle connects all stages of a product system, starting at the production phase (starting material) and the use phase up to the disposal/recycling phase (final disposal) (Heijungs et al., 2010). Other aspects, such as process costs, profit and reaction times can be closely examined with additional tools connected to LCA (Gonzalez and Smith, 2003; Finkbeiner et al., 2006). These tools enable comparison of different processes, based on available quantitative data. In addition to the comparison of different processes, these quantitative data make it possible to identify points for improvement in the process, to make it more sustainable.
The study of Tabone et al. (2010) explicitly applies the principles of green chemistry to study the environmental impact of several (bio)plastics, as well as conducting an LCA. Tabone et al. (2010) combined three sets of principles: 12 Principles of Green Chemistry, 12 Additional Principles of Green Chemistry and 12 Principles of Green Engineering (Anastas and Warner, 1998; Winterton, 2001; Anastas and Zimmerman, 2003). From the three different sets they derived nine themes (or metrics) that could be measured to obtain quantitative data. Table 1 elaborates briefly the nine different themes that were introduced by Tabone et al. (2010).
No. | Theme | Content |
---|---|---|
T1 | Avoid waste | High atom economy, keep track of by-products, good mass balance. |
T2 | Material efficiency | Maximized mass, energy, space and time efficiency (e.g., reactants in desired product, as little energy as possible). Design product that works 100% for the intended purpose. Physical characteristics. |
T3 | Avoid hazardous materials/pollution | Safe chemicals, prevent pollution, prevent instead of treatment. |
T4 | Maximize energy efficiency | Minimizes needed utilities (energy, chemicals, re-use of output). |
T5 | Use of renewable sources | Use renewables. |
T6 | Use local sources | Use local material and energy. |
T7 | Design products for recycle | Products design for separation, minimize material diversity. |
T8 | Design to degrade | (Bio)degradability of product. |
T9 | Cost efficiency | Costs as low as possible. |
The more starting material that ends up in the desired product, the more sustainable the product is (T1). The more product meets the necessary physical characteristics, the more sustainable the product is (T2). The prevention of the amount of hazardous materials and pollution (T3) is part of the ecotoxicity and human health, e.g., the less hazardous material, the better the ecotoxicity impacts. The use and re-use of all the energy and chemicals (T4) related to a product indicates the effect on the environment, and with it the sustainability of the product. The more the plastic is based on renewable sources (T5), the more sustainable a product is. Another relevant item is the use of local sources (T6); the further away raw materials are extracted, the less sustainable the product becomes due to transportation. The amount of material that is recovered from the product indicates the sustainability of a product (T7). Here too, the higher the percentage, the more sustainable, because less new material is needed. The degradability of a plastic, i.e., nonbiodegradable, biodegradable in artificial conditions or biodegradable in the environment, is an aspect of overall sustainability (T8). The cost of making a plastic (T9) can be a deal breaker, if a more sustainable plastic cannot compete in terms of costs with a less sustainable one. Tabone et al. (2010) used the themes for the production phase only, but indicated that for a proper LCA also the use and disposal scenario should be taken into account in which the same themes do play a role. The scientific paper underlines the complexity of the sustainability of plastics (or sustainability issues in general). For example, a bioplastic can score high on the green design principles by using fewer fossil fuels, but on the other hand this same plastic was obtained by growing natural material that had to be fertilized. The impact of fertilizer has some negative effects on the environment as well. From an educational point of view, the work of Tabone et al. (2010) is interesting because it adequately points out the themes (content knowledge) that should be considered to draw conclusions on the sustainability of plastics. Also, those themes are based on the 12 principles of green chemistry which are integrated in many chemistry curricula.
Compared to conventional plastics, citizens consider bioplastics to have a more positive impact on the environment, although there was some ignorance on the proper disposal of bioplastics, degradation rates, limited biodegradability and the quality of bioplastics (Lynch et al., 2017; Haider et al., 2019). The study of Boesen et al. (2019) showed that well-educated young Danish consumers think that bio-based conclusively means that it is also biodegradable. The difference between compostable and biodegradable was not clear. The study of Dilkes-Hoffman et al. (2019) revealed that Australian citizens have doubts on whether the biodegradable plastics could have a negative impact on the environment. The work of Steenis et al. (2017) showed that LCA outcomes might not always match citizens’ perceptions of the sustainability of a product. They questioned Dutch students on their perceptions of sustainability of packaging. The perceptions of these students were compared with an LCA that was performed to determine the sustainability of the different packaging materials the students could choose from. It was concluded that consumer intuitions were in some cases the opposite of the data of the LCA. In multiple research studies, it was observed that consumers perceptions were mainly based on the last phase of a product, namely the disposal phase. In particular, the influence that the consumer himself can have on this phase largely determined their considerations.
In short, the findings show that among citizens (in general) there is a positive view of bioplastics, but that there is also a serious gap in knowledge, e.g., perceptions on sustainability not necessarily based on data from LCA. In addition, it was shown that there is a concern that the prefix ‘bio’ is used as a marketing strategy because of the positive image (Haider et al., 2019). These finding underline the need for proper education and information about the environmental impact of (bio)plastics (Blesin and Jaspersen, 2017; Haider et al., 2019). It is interesting to investigate the perceptions of youngsters (age 16–17 years) related to the sustainability of (bio)plastics and the extent to which their perceptions overlap with reported perceptions of the general public. And if we are to organize education on this issue, what are the perceptions to account for, what is students’ prior knowledge base and what are the possibilities to build on this to provide students with a more coherent and complete view on the sustainability of (bio)plastics?
1. Which knowledge, scientific and other, are used by students in reasoning about the sustainability of plastics?
2. Which components are present in students’ reasoning, that is, which claims, backing, rebuttals and qualifiers can be identified?
3. To what extent does the designed student activity make the students aware of the complexity and multi-dimensionality of the sustainability issue at hand?
Table 2 shows the outline of the student activity with the various components, function and the collected data sources. The student activity can be divided into parts A and B and was carried out in an average of 2 hours. In some cases, there was a week between part A and B. The data collected in part A of the student activity is the first measurement; this measurement consists of the data sources written answers and interview I. In part B of the student activity, the second measurement is performed with the data sources written argument and interview II. The measurements are used to investigate the development of the students’ argumentation.
Activity component | Function | Collected data sources | ||
---|---|---|---|---|
A | 1 | Students watch an introductory video about a Dutch recycling company | Introduction to the subject | — |
2 | Students answer a set of questions about production, use and recycling of plastics | Make explicit students’ initial stance | Written answers & interview I (Table 3) Measurement I | |
B | 3 | Individual reading of 2 national news articles and making a summary of the articles with guiding questions | Confrontation with conflicting aspects related to bio and fossil-based plastics and recycling | — |
4 | In a group discussion the students exchange information read in the articles and revise initial stance. | Make explicit students’ final stance based on information collected | Discussion, written argument & interview II (Table 3) Measurement II |
In the first part (A) of the student activity, the goal was to investigate the initial thinking, reasoning and opinion on production, use and recycling. The group of students watched a video about a Dutch recycling company as an introduction. In this video, the recycling company showed how they separate the various flows of waste in their factory, with a focus on plastics. To introduce the students to the subject and to activate their prior knowledge about plastics in the context of sustainability, the students individually answered some questions on paper (written answers) followed by a semi-structured interview (interview I) to collect additional data for clarification and insight on the written answers given. The questions were divided into questions about production, use and recycling. This was a deliberate choice to make the students think about all three phases of the life cycle of a product. The students, however, were unaware of the division into production, use and recycling questions. The final question in part A was to take a position on the issue: which plastic, bioplastic or fossil-based, do you think is the most sustainable? The answers to this question and interview I were collected as data for measurement I.
In the second part (B) of the student activity, the goal was to reveal the students’ reasoning and content knowledge after they have read and talked about the topic. By using the Jigsaw method, the three students read two different news articles from Dutch national media containing positive and critical point of views related to the production, use and recycling of (bio)plastics. Through answering questions, the students were guided to understand the position of the articles (the questions posed are shown in Appendix 1). Together, the students read six news articles and discussed the content in a group discussion, which was chaired by the researcher. By sharing the (contradictory) information in the news articles, discussions were evoked among the students, which were encouraged by the chair. The answers to the guiding questions (Appendix 1) were used to keep the discussion going. The news articles were selected based on three criteria, namely (1) presence of all nine Tabone's themes, (2) the presence of all three phases of the life cycle and (3) the readability of the article from a student's perspective.
After the group discussion, the students were asked to give their final opinion on the written argument on the same issue as in part A: which plastic, bioplastic or fossil-based, do you think is the most sustainable? In semi-structured interview II, the students were asked to clarify, if needed, their answers and to get some additional information on missing information and motivation (protocol in Table 3). Written argument and interview II represent the data collected in measurement II.
Written answers | Interview I | ||
---|---|---|---|
Measurement I | Production 1 (p1) | What do you know about the production process of a plastic? | After reading the answers of the students, the researcher asked clarifying questions on the given answers, with specific attention for main questions (last question written answers). |
Production 2 (P2) | When is production sustainable? | ||
Use 1 (u1) | What requirements do you impose on the plastic that you use every day? | ||
Use 2 (u2) | What do you think of the compulsory fee we have to pay for a plastic bag in the shops? | What answer did you gave at the q2? | |
Recycling 1 (r1) | How would you define recycling and reusing? | – What arguments did you use? | |
Recycling 2 (r2) | What do you think of the fact that China has processed our plastic waste for a while? | – On which facts did you base your answer? | |
– Which possible doubts and/or questions do you have with your answer? | |||
All phases 1 (q1) | Write down any questions that came up during the introductory film and the questions: | Further questions for clarification were asked to obtain additional information. | |
All phases 2 (q2) (main question) | – What plastic do you think is more sustainable? Options are (1) fossil-based plastic, (2) bioplastics or (3) do not know. | ||
– What arguments did you use? | |||
– On which facts did you base your answer? | |||
– Which possible doubts and/or questions do you have with your answer? |
Written argument | Interview II | |
---|---|---|
Measurement II | 1. What plastic do you think is more sustainable? | 1. Did you change your stance, or do you hold to your previous one? |
Bioplastic | Yes: What information supports your stance? | |
Fossil-based plastic | No: What information caused the change of opinion? | |
Do not know | 2. Did new information caused you to doubt? | |
2. On which facts did you base your answer? | Yes: What new information has brought you to doubt? | |
3. Which possible doubts and/or questions do you have with your choice? | 3. If you have any doubts about making a choice, what would you like to know as information to make a more confident choice? | |
4. Would you be motivated to investigate this in a chemistry lesson? |
The group discussion was initiated by the chair by first asking the students to clarify, explain and share the information they acquired through reading the articles. Next, the chair posed questions to the group to keep the discussion going, e.g., “Tell the others the important things you have read in your articles,” “Read your previous answer on p2, u2 and r2 again and indicate if you would like to change something or add something to your answer.” The same procedure was followed for the answer on q2. Also, spontaneous discussions on information and opinions students shared with each other were encouraged. Finally, students individually stated a written argument and the first author conducted an individual interview. Table 3 shows the written arguments as well as the protocol for interview II. The written arguments cover the students’ argumentation on the sustainable issue related to bio- and fossil-based plastics. Interview II was used to clarify why the students held or changed their position on this sustainable issue.
The first data collection was to capture students’ initial reasoning, with the least influence from others (measurement I). Statements in the written answers and interview I in which students substantiated their choice of the most sustainable plastic were selected by the first author. The total number of relevant statements from interview I and the written answers was 106.
To capture the final, more influenced, reasoning, the second data collection was done from the written argument, group discussion and interview II. The topics plastics and sustainability were discussed throughout the complete group discussion. However, only the parts of the groups discussion in which the students discussed their choice of plastic, substantiated their choice of plastic and/or put forward counter-arguments for not choosing their plastic, have been selected and transcribed. These selections varied from 7 to 20 minutes in total per group. The total number of relevant statements, from the written argument, interview II, group discussion and interview II was 136.
The data were analysed using a qualitative content analysis strategy (Schreier, 2013). First, a coding scheme was developed containing (1) the Tabone's themes as elaborated in the theoretical background (Table 1), (2) the categories of an adapted version of the argumentation model of Toulmin (2003) and (3) the phases in the cycle, i.e., production, use and recycling. Second, six additional non-Tabone themes were added to the original nine Tabone's themes. Third, the quotes were coded on three different levels, namely the appropriate theme, Toulmin's category and appropriate phase in the life cycle.
Fig. 1 An adapted version of Toulmin's argumentation model (Toulmin, 2003). |
In Table 4, some examples of the coding of the statements are presented. The inter coder agreement was tested by calculating the percentage of statements coded equally by two researchers (first and second author of this paper). The first author selected eleven statements for each group, five from measurement I (from written answers and interview I) and six from measurement II (from written argument, group discussion and interview II). In total, 99 statements were coded independently by two researchers. This is 41% of the total data set. The inter coder agreement for Tabone's themes was 80% and 74% for Toulmin's categories.‡ Taken together, the inter coder agreement was 78%. In literature, 70 percent is regarded as the lower limit for a sufficient level of agreement, and 80 percent for a substantial level (Miles and Huberman, 1984). In the present case, we regarded 78% as a sufficient level of agreement, taking into account that the Tabone's themes are rather broadly formulated and do show overlap. We also analysed the statements coded as ‘non-Tabone’ in more detail to reveal new themes that emerged from the data. Five new themes were identified which were labelled as (1) direct comparison of bio vs fossil (NT10a), (2) bio as misleading term (NT10b), (3) agricultural land (NT10c), (4) pros and cons (NT10d3) and (5) behaviour society (NT10e). Any remaining statements were coded as miscellaneous (NT11). Next, the complete research team discussed the results to identify major trends and findings.
Student quotes | Tabone's themes | Toulmin's categories | Phase | |
---|---|---|---|---|
1. | Fossil-based plastics last longer and can be reused better, they stay in the ‘use’ phase longer [description of own experience] | T2 | Data | Use & recycling |
2. | Whether the production [of bioplastics] creates much less CO2 emission and is less environmentally polluting. | T3 | Missing information | Production |
3. | Fossil-based costs a lot of energy because of the drilling | T4 | Backing & warrant | Production |
4. | Fossil raw materials can run out | T5 | Data | Production |
5. | And the transport of all raw materials is also very important | T6 | Qualifier & rebuttal | Production |
6. | I think it is better if there are fewer types of plastics, so that it can be sorted more easily. This way more can be recycled. | T7 | Qualifier & rebuttal | Recycling |
7. | Are the bioplastics easily degradable in nature? | T8 | Missing information | Recycling |
8. | How expensive are bioplastics? | T9 | Missing information | Not phase related |
9. | This is actually under one condition. There must be campaigns from the government or non-profit organizations that make people more aware of what biological plastic means (claim: bioplastic) | NT10e behaviour society | Qualifier & rebuttal | Not phase related |
10. | I just believe that [fossil-based] plastic does its job very well | NT11 | Backing & warrant | Not phase related |
Tabone's themes | Number of groups | Toulmin's categories | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Data | Backing & warrant | Qualifier & rebuttal | Missing information | Total | ||||||||
I | II | I | II | I | II | I | II | I | II | |||
T1 | Waste | 0/9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
T2 | Efficiency | 9/9 | 3 | 1 | 5 | 5 | 0 | 0 | 3 | 3 | 11 | 9 |
T3 | Pollution | 8/9 | 6 | 10 | 5 | 5 | 0 | 1 | 3 | 5 | 14 | 21 |
T4 | Energy | 3/9 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 2 | 2 |
T5 | Renewable | 8/9 | 19 | 10 | 2 | 3 | 0 | 2 | 2 | 1 | 23 | 16 |
T6 | Local sources | 1/9 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
T7 | Design recycle | 8/9 | 0 | 0 | 4 | 7 | 0 | 10 | 4 | 6 | 8 | 23 |
T8 | Design degrade | 9/9 | 0 | 0 | 9 | 9 | 0 | 3 | 3 | 6 | 12 | 18 |
T9 | Costs | 4/9 | 0 | 0 | 1 | 5 | 0 | 1 | 0 | 1 | 1 | 7 |
NT10a | Comparison | 8/9 | 0 | 0 | 5 | 3 | 0 | 1 | 7 | 5 | 12 | 9 |
NT10b | Prefix ‘bio’ | 7/9 | 0 | 0 | 10 | 5 | 1 | 3 | 0 | 0 | 11 | 8 |
NT10c | Agricultural | 4/9 | 1 | 0 | 0 | 2 | 0 | 2 | 4 | 0 | 5 | 4 |
NT10d | Pros & cons | 5/9 | 0 | 0 | 0 | 7 | 0 | 1 | 0 | 0 | 0 | 8 |
NT10e | Society | 6/9 | 0 | 0 | 2 | 3 | 0 | 5 | 1 | 0 | 3 | 8 |
NT11 | Miscellaneous | 4/9 | 1 | 0 | 2 | 2 | 0 | 0 | 1 | 0 | 4 | 2 |
Total | 30 | 21 | 46 | 56 | 1 | 31 | 29 | 28 | 106 | 136 | ||
Number of groups | 9/9 | 9/9 | 9/9 | 9/9 | 1/9 | 8/9 | 9/9 | 9/9 |
The total number of statements that were coded as a non-Tabone subcategory were 35 and 39 for measurement I and II respectively. Below, we elaborate on the two most often mentioned themes NT10a and NT10b, in which the students discuss (1) the comparison between fossil-based plastics and bioplastics and (2) the influence of the prefix bio. In the NT10a category, questions were raised about the ecological footprint of both plastics. In most cases, students did not compare the complete cycle of bio- and fossil-based plastics, but zoomed in on a single step or instance in the cycle for which they lacked information. For example, students claim that the impact on the environment is comparable both for the production and the recycling of bioplastics and fossil-based plastics and stress the need for more information regarding the use phase and its impact on nature. As for NT10b, students admit that they think that bioplastics are the most sustainable due to the stereotype ‘bio is environmentally friendly’. Students mention that media and social media play a role in this, because most of the time the fossil-based products/materials are portrayed poorly and the biological products/processes are portrayed as good. Students themselves, at some point, raised the question whether it is misleading to use the prefix bio, as typified by the following statement:
‘It is better for the environment, but the word is misleading.’ – student 16 written argument
Considering the original Tabone's themes, it can be concluded that T2, 3, 5, 7 and 8 were the most frequently mentioned by the majority of the groups (8 or 9). These categories describe matters related to efficiency (materials), pollution (e.g., CO2, greenhouse effect) and design of products with the possibility of recycling or (bio)degradability. In contrast, T1, 4, 6 and 9 were mentioned the least, respectively by 0, 3, 1 and 4 groups. The latter themes include matters related to avoiding waste, energy efficiency, the origin of energy and materials, and costs. Statements related to costs were predominantly mentioned in measurement II.
Below, we portray the four frequently used Tabone's themes in more detail and give some descriptive examples of students’ arguments. Quotes related to T3 are mainly focussed on CO2 emission. The fossil-based plastics are responsible, according to the students, for the emission of CO2 into the atmosphere, and contribute to the greenhouse effect. In addition, some students wonder what kind of substances are actually emitted apart from CO2. In general, many students just state that fossil-based plastics are the most polluting for the environment, or vice versa, that bioplastics are the least polluting, without further substantiation. In the T5 category, the students mentioned that fossil resources are running out, evoking a need for alternatives for fossil-based plastics. A frequently mentioned argument is that society needs to become more efficient in the use of fossil raw materials and/or alternatives are needed. Other statements in the theme are focussed on the biological raw materials and the fact that they are renewable. As for theme T7, what becomes evident from the students’ arguments is that they perceive that the recycling process of bio-organic materials is easier. Students often posed questions related to the recyclability of fossil-based plastics. Notably, students made connection between T2 and T7, e.g., they argued that since fossil-based plastics are much stronger (T2) it is much harder to break them down and to recycle them, as typified by the statement below:
‘I may be completely wrong, but fossil-based products are generally stronger than bio-based products, which makes them less likely to break down and less easily to recycle’ – student 25 Interview I
During measurement II, students indicated the complexity of the recycling process, based on one article that described the difficulties encountered by recycling companies dealing with many different types of plastics. They started to question the recycling of both fossil-based plastics and bioplastics and indicated that the choice of the most sustainable plastic does depend on how easily a plastic can be recycled. Students expressed a need for more information/data for this aspect. Related to T8, many students argued that bioplastics are easily absorbed and digested by nature. For those last two discussed categories (T7 and T8), it was observed that some students faced difficulties distinguishing between recycling and degradation. In most cases, it was possible to separate the statement into two statements. An example is given below, in which the student discussed T8 in the first part of the statement and T7 in the last part.
‘Bioplastics are biodegradable, so if you leave them behind [in nature] it just goes away and that is not the case with fossil-based plastics, so that is more recyclable.’ – student 26 interview I
Comparing measurement, I to II, the results show an increase in students arguments related to recycling (from 8 to 23) and pollution (from 14 to 21). A possible reason for this increase might be that four articles zoom in on the concept of recycling and that pollution was a recurring theme in the group discussions.
Some statements could not be assigned to any of the phases, since it was (1) unclear what phase(s) the students were talking about and/or (2) the statements reflected the image of society about the sustainability of plastics influenced by the media or campaigns. In these cases, the focus is on peripheral matters that do play a role in a sustainable issue.
In measurement II, nine students altered their claim about the most sustainable plastic. Those nine students came from five different groups. Two groups completely changed their claim. In one of those groups, all three students claimed bioplastic in measurement I; after the student activity all students changed their claim to do not know. In the other group, two students claimed bioplastic and one student do not know. After the student activity, they changed their claim to fossil-based and bioplastic respectively. Three students from three different groups changed their claim from bioplastic to do not know. Two of them came from a group that chose only bioplastic and one of them came from a group in which one of the other students chose fossil-based and the third student chose bioplastic.
So, after the student activity, a shift in the distribution of the claims was seen. Several students indicated that they strongly doubted their earlier claim, resulting in changing their claim to do not know. The students that changed their claim to do not know expressed their doubts by mentioning the information they read in the articles or what they heard from the other students during the group discussion (e.g., difficulties in the degradation process of bioplastics, the use of agricultural land and the competition with food, and the influence of the behaviour/knowledge of society). The students also made statements about the advantages and disadvantages for both types of plastics, however, this was limited by the students indicating that they missed information. According to the students themselves, they could not make a proper comparison, resulting in becoming indecisive about the most sustainable plastic.
Two students changed their claim from bioplastic to fossil-based plastic. For these students, who came from the same group, the argument was mainly that if we as society were to use a single type of plastic, we as society would have less problems in the recycling process. One of the two students who hold the claim fossil-based plastic also explained that there is no problem with the use of the strong fossil-based plastics, but we have to handle them more neatly and recycle 100%. There was also a student who changed the claim from do not know to bioplastics. For this student, the fact that bioplastics are produced from a material that is an inexhaustible source was a valid and important argument to be sure about their choice for bioplastics as the most sustainable.
In total, sixteen students stuck to their claim that bioplastic is the most sustainable plastic. However, ten of these students expressed (small) doubts or said that they felt more uncertain about their claim because of the student activity. Their doubts were in some cases phrased as a qualifier and rebuttal, but despite their doubts they kept their claim (bioplastics) because the advantages outweigh the disadvantages. These ten students came from five of the nine groups. The other six students that held their claim on bioplastics indicated that they were more certain or said that they had no doubt after the student activity. These students came from five different groups.
The focus of the first question was mainly on the use of the 12 principles of green chemistry as embodied in the Tabone's themes. The results of our research have shown that a number of Tabone's themes are not spontaneously used in the reasoning of the students (T1, 4, 6 and 9), and some of the themes are mentioned regularly (T2, 3, 5, 7 and 8). This indicates that T2, 3, 5, 7 and 8 are part of students’ prior knowledge. However, T1, 4, 6 and 9 require more attention to familiarize the students so that these themes also become part of their knowledge and reasoning. In addition to the predefined Tabone's themes, we identified a number of additional themes in the statements of the students. These statements, overall, portrayed a more general approach or had to do with society related matters. These non-Tabone themes were mentioned in measurement I as well as II, so these non-Tabone themes are part of students’ prior knowledge. We regard students’ comments regarding the misleading image of the prefix ‘bio’ as remarkable. In our opinion, this testifies to a critical view of the term that is frequently used for many products. The mentioned non-Tabone themes by students do comply to large extent with the ethical and ecological categories as defined by Juntunen and Aksela (2014). The non-Tabone themes NT10a and NT10e fall within the ecological category, whereas the themes NT10b, NT10c and NT10d relate to the ethical category. Our study supports the findings of Juntunen and Aksela (2014) that students’ arguments cover multiple dimensions next to a pure scientific one. Our study gives insight into the content of the scientific, ethical and ecological arguments put forward by students. In addition, our study shows some similarities between the perceptions of the citizens (the elderly) surveyed and youngsters in secondary school. Studies into citizens’ perceptions of bioplastics have shown that the image of bioplastic is generally positive and generates positive associations, such as more environmentally friendly and more sustainable. From the literature, it is known that T2, 3, 8 and 9 occurred in the argumentation of the citizens. In our study, T2, 3 and 8 were also part of the most-mentioned themes in the students’ argumentation. Also, ignorance and more negative aspects found in citizens, such as land use and more short-lived products, were broadly in line with the perceptions found in students. In short, the results in this study indicate which content knowledge students bring in when confronted with the sustainability issues regarding plastics, as well as which content knowledge is absent or hardly used by students using Tabone's themes as frame of reference. This information is of valuable use when designing education in which students are engaged in LCA on plastics. It reveals the prior content knowledge of students to build on and elaborate and clearly shows content knowledge to account for.
The second question was focussed on the structure of students’ arguments, i.e., are the students able to provide a well-founded argument with enough support for their statement? In general, the arguments of the students appeared to be fairly complete. All of the Toulmin's categories could be assigned multiple times. The students proved able to discuss this subject at a fairly complete level. The adapted Toulmin's model proved appropriate to analyse the (at this stage) still rudimentary students’ argumentation. The students did not have not much time to think about their claim in this relatively short student activity. In addition, the students were not trained in giving a complete argument on LCA of plastics. This adaptation follows some critics in literature on Toulmin's model claiming that it is difficult to distinguish the different categories (Erduran et al., 2004). Also, the context in which the student express their argumentation matters (Kelly et al., 2007). The addition of the category missing information made it possible to include the questions of the students in their arguments, related to the context of production, use and re-use of plastics. We regarded the lack of knowledge as expressed by students as a valuable component of student argumentation. Most of the Tabone's themes were found in the Toulmin's categories warrant & backing, missing information and qualifier & rebuttals. Only a few of the Tabone's themes were assigned to data (T3 and T5). This, however, could be a consequence of our rather strict definition of Toulmin's category data, i.e., empirical data, experience and/or generally accepted knowledge. It is possible that a number of students’ statements did not fit this definition of category data and ended up in other categories.
Regarding research question 1 and 2, in this study we did not analyse the quality of students’ arguments and focussed only on the structural components in their arguments. This complies with the goal of this study, as we were interested in the kind of argumentations students put forward initially, including the content knowledge they use. Examples of (partially) incorrect statements are, for example, claims that bioplastics are easier to degrade by nature, easier to recycle, that bioplastics are easier to produce and/or that bioplastics thrown in nature will soon disappear. These statements surely require more substantiation and more scientific underpinning. However, these kinds of (partly) incorrect or less underpinned statements will also pop up during chemistry classes and thus offer opportunities to use as starting point for discussion with students. However, if students come up with more sophisticated arguments, other models for analysis of arguments are needed.
The third research question was focussed on the awareness of the students of the complexity and the multi-dimensionality of the sustainability issue. It was observed that the students were able to reason on this sustainable issue. All phases of the life cycle were present in the students’ argumentation. From this, it can be concluded that the student activity was successful in guiding students to reflect on all phases of the life cycle. In our opinion, this is a remarkable finding because earlier studies have revealed that the last recycling phase in particular is considered when thinking about life cycles (Steenis et al., 2017; Boesen et al., 2019; Dilkes-Hoffman et al., 2019). During the student activity, the students discovered that the easy-looking question was more complex than they initially thought. Doubts were raised during the student activity, as identified by the increasing number of qualifier & rebuttals. In literature, the increase of rebuttals is regarded as an indication of an increasing and deepening level of reasoning (Erduran et al., 2004). The shift in claims during the student activity shows that the students start to think more critically about their claim, particularly evidenced by the increase in the number of claims do not know from measurement I to II. Apparently, some students are unable to make a good choice between the bioplastics on the one hand and the fossil-based plastics on the other. The expressed doubts, to a lesser extent, were also visible in the statements of the students who nevertheless maintained their claim.
This explorative study provides indications and guidelines for the design of an intervention aimed at fully engaging students in LCA on plastics. The students’ arguments, in general, are rich with aspects both falling within the Tabone's themes (scientific arguments) and outside the Tabone's themes (socio-cultural arguments). The students showed to be able to reflect critically on their claim, and some adjusted their claim based on other arguments or opinions brought in. These findings show that the students are sensible to the complexity of the issue of sustainable plastics and underline the suitability of this context for reasoning about sustainability. Previous studies have revealed that students, in general, have a tendency to make their claims without adequate justifications and put forward primarily socio-cultural arguments as they touch upon their own opinion and world as experienced (Juntunen and Aksela, 2014). In addition, Osborne et al. (2004) claims that students need time to search for information or learn the topic first in order to bring in scientific arguments. The results in our study, however, show that students are using scientific arguments in their argumentations relatively short after introduction of the sustainability topic. In our opinion, this is an indication that the student activity was well designed and functioned adequately. The essence of the student activity was the comparison of two plastics on sustainability. Comparing two arguments helps students to realise the importance of justifying their claims (Simon, 2008). The student activity presented and tested in this study seems to be suitable to use as an introduction in a larger curriculum unit on sustainability issues related to plastics.
Although the results are based on a relatively small test group, the findings provide relevant input for design of interventions focussed on engaging students in LCA on plastics. In this respect, it is needed to account for the Tabone's themes (T2, 3, 5, 7 and 8) which might be regarded part of students’ prior knowledge as well as under-represented Tabone's themes in students’ argumentations (T1, 4, 6 and 9). To bring the Tabone's themes into focus, both theoretical and practical (lab)work might be considered. For example, calculating the amount of waste produced during the practical assignments might contribute to the meaning of the production of waste (T1), including the impact it has on the sustainability of a product. In addition, doing practical (lab)work also offers opportunities to make students aware of the efficiency of utilities (T4), e.g., students can research the origin of the raw materials. While the Tabone's themes mainly offer a scientific perspective on sustainability issues related to plastics, the non-Tabone themes mentioned by students give input for organizing class discussion about the broader socio-cultural aspects.
Generally in ESD, students tend to exclude scientific knowledge from their personal knowledge (Sadler, 2004). This study indicates that students are able to bring in relevant scientific knowledge when confronted with a suitable SSI context. However, there is still a need for creating science education that fosters students’ content knowledge in performing LCA. Future studies should aim to find effective means to incorporate LCA in chemistry education. It is worthwhile that students, as future citizens, are aware of and practice skills that come with performing LCA on products and processes. Having well-documented examples, as well as more understanding of the effectiveness of teaching approaches on conducting LCA in chemistry education, is crucial for improving ESD in 21th century chemistry classrooms and for making society more sustainable.
Guiding question for reading articles | |
1. | From which two perspectives have you read the two articles (positive or negative point of view)? |
2. | What is the central claim of each of the two articles? |
3. | What do the two articles agree on? |
4. | What do the two articles disagree on? |
5. | For each article, write down the most important arguments according to you. |
6. | Which article matches best with your own opinion? What does this say about your position? |
7. | Do you think the organizations that give the information in the article are reliable sources? |
Footnotes |
† The term ‘Tabone's themes’ refers to the nine different themes as identified by Tabone et al. (2010) for performing LCA on plastics. |
‡ The term ‘Toulmin's categories’ refers to the categories in the adapted version of Toulmin's argumentation model (Toulmin, 2003) as portrayed in Fig. 1. |
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