1. Introduction
The widespread acquisition of electronic devices has presented an additional environmental challenge: the management of electronic waste once the devices reach the end of their lifecycle. In 2021, 74% of young people already had access to handheld devices at home, e.g., mobile phones or tablet computers, especially iPads [
1]. The relevance of the iPad results from its versatile use and high prevalence [
2]. One of the materials used in the iPad is plastic. Therefore, it represents a relevant context for learning about plastics chemistry. In addition to its function as a learning context, the iPad can also be used as a digital learning tool in digitally enriched learning scenarios, e.g., to watch videos or access augmented reality (AR) content [
3]. AR is a continuum of reality and virtuality and is defined through 3D registration, merging of real and virtual content, as well as real-time interactivity [
4,
5].
With iPads in schools, a changed learning culture could come to pass, which is characterized by collaborative, communicative, and student-centered teaching concepts [
6]. Furthermore, learning success can be proven using tablets, which, however, is presumably dependent on the digital competencies of the teacher [
6]. Through the hardware and software, it is possible to combine reality and virtuality using iPads, which opens up new, cost-effective, school-based uses for augmented learning content. The ability to represent chemical facts at the particle level using AR, and thus bring non-intuitive content closer, can reduce misconceptions on the part of learners, promote their understanding, and thus lead to an increase in performance [
7,
8,
9]. Insights into devices, such as an iPad and technical equipment that are not normally possible, can also be realized using AR. In addition, enriching analog media with AR and other (multimedia) content, such as videos, graphics, etc., supports the effectiveness of digital teaching–learning materials [
10]. Furthermore, AR can be used to create differentiated learning opportunities and thus promote learners’ learning growth, perceived self-efficacy, and self-regulation [
11,
12,
13]. Moreover, it could be shown that AR learning scenarios are able to evoke situational interest and can help simplify understanding [
14,
15]. As reported by Yu et al. [
16], students find AR learning scenarios helpful and effective.
In the project “Rare Earths & Co in Digital Sustainability Education”, the focus is explicitly on the materials of the iPad, which is increasingly used by young people in their private lives and the school context [
17,
18]. The aim is to provide learners with digitally enriched, modular learning environments to give students an insight into the iPad and to address materials used in it as well as the resulting problem of waste. The project’s focus on handheld device learning is influenced by three key concepts: relevance in science education [
19], socio-critical and problem-oriented science teaching [
20], and systems thinking [
21]. Therefore, the augmented learning environment engages students to explore tablet sustainability’s environmental, social, and economic impacts. Based on the main components of a tablet—battery, circuit board, case, display, and plastics/adhesives—five learning scenarios have been developed for grades 9 to 13. Each scenario covers five areas: disassembly, properties, production/function, recycling, and raw material substitution. Small modules on life cycle analysis are also included. Methodologically, the learning scenarios consist of digitally enriched theory stations (e.g., enhanced interactive elements, explanatory videos, and animations) and two to four experiments. The latter can be carried out physically or digitally so that the learning scenarios can also be used remotely, regardless of location, while avoiding security risks. The time frame (usually 3 h in total) and the thematic focus can be adapted to the learning group due to the modular structure of related subtopics. The sustainable use and effective recycling of the tablet hardware as learning objects are also digitally enriched in terms of methodology and media didactics through learning with the tablet. This dual instrumentalization of the tablet is one of the distinguishing features of the project. In recent years, various augmented learning scenarios have been created within the project, such as neodymium in speaker magnets or lithium-ion batteries, among others. In addition to the subject of chemical content, sustainability aspects, as well as the handling of these materials at the “end of life” of an iPad or their substitution possibilities, are particularly considered [
22].
The following paper presents a new didactic approach to how an iPad-related consideration of the properties, production, processing, recycling, and use of plastics, as well as possibilities to replace them, can take place in a tablet-based digitally enriched learning scenario. The use of digital technologies such as AR enables a new perspective on and into the content of plastics chemistry in class. This allows not only the basic content of this subject to be addressed but also areas and perspectives such as highly relevant sustainability aspects of digital devices.
4. Learning Scenario
The conceived learning scenario was developed to promote students’ situational interest and understanding of crucial sustainability issues related to plastic waste—both through the use of tablets as learning tools and subjects and through the integration of AR applications. The learning scenario was developed as part of the project “Rare Earths and Co in Digital Sustainability Education” and is suitable for grades 10 to 13. The learning scenario is divided into five sub-topics with analog, digital, and experimental content that can be worked on independently by learners in groups of two or three in any order. Four of the stations are also enriched with augmented reality learning content, which enables new perspectives on and into the content of plastics chemistry, particularly at the particle level. The contextual basis of the scenario is the consideration of plastics as components of an iPad. Thus, the iPad is not only the learning tool but also the learning object itself. For this purpose, the scenario takes a phenomenological view of plastics, using the particle level to explain corresponding material aspects (including structure–function relationships). The consideration of the symbolic level, according to Johnstone [
26], is completely omitted. Therefore, as well as the extension of the topic by aspects of sustainability and criticality, the learning unit is recommended as a supplement to regular chemistry lessons. Individual sub-topics can be selected and worked on as needed. The components of the iPad are discussed, such as the proportion of plastics in the components used, the properties of plastics, the manufacturing processes for plastics, and the possibilities for recycling and substitution. Therefore, before using the material, the definition of plastics and their synthesis pathways at the particle level should have been taught.
4.1. Design and Used Programs
When creating the learning environment, Gestalt principles, according to Böhringer et al. [
27], and the principles of multimedia learning (including [
28,
29,
30,
31,
32]) were taken into account. Maya 2023 software from the developer Autodesk Inc, San Francisco, CA, USA. Was used to create and animate the 3D models. The AR applications were created using the ZapWorks Studio authoring tool from Zappar Ltd., Auchterarder, UK. These applications can be accessed by scanning the Zapcode with the free Zappar app from the same developer. YouTube learning videos were integrated into the learning unit through the learningapps.org website. This website allows excerpts of YouTube videos to be shown and, among other things, prevents other content from being displayed to students. A PowerPoint presentation is provided to visualize content (hints, QR codes, etc.) during the introduction and follow-up. The tool “genial.ly” was used to create further digital, interactive content.
4.2. Introduction
To introduce the learning scenario, students’ associations with the colloquial term plastic are collected, for example, as a Wordcloud via the online tools Mentimeter or Answergarden. In addition to examples and properties of plastics, learners are likely to address the negative aspects of plastics released into the environment. This points to the future significance and authenticity of the topic. Following this, learners are asked if and what kind of items made of plastics they carry, highlighting the relevance to all areas of learners’ everyday lives. The term critical raw material or criticality is then introduced and briefly explained using an example such as cobalt. The students are then asked to make an initial assessment of whether plastics could be a critical raw material. In the course of this, the central problem question of the learning scenario is presented to the learners by the teacher: “Should plastics be used as materials for iPads (and other things)?”. As a transition to the digital learning environment, the learners receive information about the procedure, time, safety regulations, and material.
4.3. Sub-Topic 1: Construction of an iPad with a Focus on the Plastics Used in the Components
The first sub-topic deals with the assembly of iPads with a special focus on plastics used in the installed parts. In advance, the adhesions were loosened, the lithium-ion battery removed, and screws and plugs colored to facilitate disassembly and assembly, avoid errors, and reduce potential danger. By scanning the QR code, learners can access the digital disassembly/assembly instructions. With these, learners disassemble the iPad and remove the speaker, front camera, and LCD, among other components. Components that the learners cannot remove are available in a separate envelope. Subsequently, learners are prompted to ascertain the relative proportion of plastic in the components. To accomplish this, learners weigh the plastic parts and calculate, utilizing the information available in the AR, the quantity of plastic in grams integrated into an iPad. The disassembled iPad is positioned on the surface with the Zap code to activate the AR, thereby obtaining information on the relative plastic content. Scanning the code activates an image-tracking AR, allowing learners to assign names to the significant visible components of the iPad (
Figure 1). You can find this Zap code and image-tacking files, as well as all the following ones, under the
Supplementary Materials.
By touching the respective text box, the learners receive a brief description and the relative plastic content of the component (
Figure 1). After the learners have calculated the plastic content [g] of the iPad, they reassemble the iPad. Due to its relevance to everyday life and the high reference to the iPad, the learners then deal with the plastic content of an Apple Pencil and the corresponding charging cable. Both objects are available to the learners, among other things, for weighing. However, learners cannot dismantle these, as it can only be realized with considerable additional effort and a higher risk of injury. Instead, disassembly is simulated by a world-tracking AR (
Figure 2). By scanning the Zapcode (v2-460-9f4ecc1-dirty), they can place the augmented Apple Pencil in the real world (world tracking) and view it from all sides. You can choose between the Apple Pencil (
Figure 2) and the charging cable, as well as the assembled and disassembled view.
Through world tracking AR, the students can view the individual components of the Appel Pencil or charging cable from all sides and physically approach or move away from the Appel Pencil/charging cable, zooming in or out. The text boxes in the blast view name the component and provide information about the materials contained there (
Figure 2). Based on this, the learners should estimate how high the relative plastic content is in grams. The determination of the plastic content is intended to help students understand the relevance of plastics in the manufacture of technical end devices.
4.4. Sub-Topic 2: Properties of Plastics
In this sub-topic, students experimentally investigate the density and malleability of selected plastics or plastic products. The aim here is for the learners to explain the use or non-use of plastics in the iPad based on various material properties and to be able to explain the properties of the three types of plastics (elastomers, thermosets, and thermoplastics) at the particle level, made visible through an animated three-dimensional AR model.
In the first experiment, the students determine the density of polystyrene quantitatively and of polypropylene qualitatively. To do this, they place both samples in a beaker filled with water and add a measured amount of table salt until both plastic samples swim. The dissolved amount of table salt is then used to calculate the density of polystyrene. Here, the students discover that there are plastics that have both a lower and a higher density than water. Then, in the second experiment, the students test the deformability of three everyday products: rubber band (vulcanized rubber—elastomer), plastic film (PE—thermoplastic), and iPad circuit board (epoxy resin base—thermoset). Learners evaluate, based on their observations, the tensile strength and reversibility of the plastic samples. After the experiment, learners scan the Zapcode, which brings up an animated three-dimensional AR model of the three plastic types at the particle level (
Figure 3).
By tapping on one of the three plastic types, the corresponding 3D model appears, and a text box explaining the structure and the behavior is shown. At the button “An Kunststoff ziehen”, an animation of the models runs, illustrating the behavior of the polymer chains when a tensile load is applied to the plastic sample at the particle level (
Figure 3). The enrichment of the real experiment by visualizing the invisible through an animated three-dimensional AR model facilitates understanding the structure–function relationship of the plastic types. The experimental investigation of further properties was omitted for time and safety reasons. With the help of the contents of the AR and their preceding experimental observation, the learners should be able to name the respective plastic types of the examples used. In addition, they should explain how the selected plastic samples would behave when heated based on the molecular structure. To be able to introduce properties that are less easily or reliably determined experimentally and to compare the material properties of plastics, the densities, thermal conductivities, and melting temperatures or melting temperature ranges of various plastics and metals were given in a data table. Finally, the learners fill in a digital cloze via the LearningApps.org platform, where students fill in the blanks in a text with the correct words. Based on the experimentally collected data and the data table, reasons can be named for using or not using plastic components in the iPad.
4.5. Sub-Topic 3: Production and Processing of Plastics
In this sub-topic, the students deal with various aspects of the production and processing methods of plastics. For this purpose, three processing methods were selected that are frequently used and presumably applied in the production of iPad components. In addition to reactions or reaction mechanisms for manufacturing, the influence of additives on the properties of plastics, toxicological aspects of the reactants, and other aspects for evaluating criticality are addressed, such as demand, country risk, and country concentration. Learners obtain the related information by scanning the QR code. This brings up an interactive text designed with genial.ly. By clicking on one of the info buttons, learners receive elaborative information, definitions, videos, 3D animations, images, or diagrams. The law of figure-ground separation and the coherence principle were taken into account so that the interactively embedded content is better perceived by the learners and is relevant and appropriate to the respective text passage [
27,
30]. Using the text, learners assess country risk, concentration, and demand for plastics. Application or transfer questions relate the key points of the text to the iPad or its components, making the iPad the learning object. For example, learners should explain how a charging cable could be made from a thermoplastic rigid plastic using additives and name the processing method for the plastic coating. Finally, the learners explain the use of additives in the production of an iPad circuit board (based on an epoxy resin). The production of an epoxy resin or thermoset is shown with an animated three-dimensional AR model (image tracking), including explanations to dynamically demonstrate the viscosity change due to crosslinking of the polymers, which cannot be directly visualized through a static image or video (
Figure 4).
4.6. Sub-Topic 4: Recycling of Plastics
The station focuses on recycling and separation processes for plastics and the associated problems. The station begins with a video on a German plastics company that operates in a circular economy, which can be accessed via a QR code. The video gives learners an insight into industrial processes and their benchmarks. In addition, the steps of (mechanical) plastics recycling are shown and explained in how “real” plastics recycling would work and which hurdles exist. In the corresponding tasks, these contents are to be reproduced and secured. The three recycling processes for plastics are taken up again in an information text explaining existing problems, including the cost factor or the need for clean separation of the different types of plastics. In the associated application and transfer tasks, the content is related to the iPad. For example, the learners assess the disposal and resulting recycling potential of the black thermoplastic iPad components or explain why an iPad contains relatively few recycled plastics [
33]. Based on the information gathered so far, learners can take a position on whether exporting plastic waste is problematic and rate the recycling potential of plastics on a scale of 1 to 5. Finally, learners solve a logic problem to separate five (hypothetical) mixed plastics. The learners receive information on the density and solubility of the five plastics (PS, PA, PET, PMMA, PE) as well as access an interactive digital separation process designed with genial.ly (
Figure 5).
4.7. Sub-Topic 5: Substitution
This station focuses on alternatives to conventional, fossil-based plastics. The aim is for the students to be familiar with the term “bioplastic” after completing this station and to be able to question its occurrence in everyday life critically. In addition to naming alternative starting materials for plastics production, the learners should also become able to describe the synthesis of a polymer at the particle level, visualized through an animated three-dimensional AR model. To be able to evaluate biobased plastics as an alternative to fossil-based plastics, the learners have to deal with their advantages and disadvantages.
The task sheet’s processing requires considering the interactive life cycle of a bioplastic designed with genial.ly, which is divided into four fields. The fields build on each other and must be processed in the order the cycle specifies. Content-related tasks accompany this on the learner’s worksheet. By embedding interactive elements in the life cycle, it is possible to obtain additional information on each field in the form of (illustrated) info texts, images, an AR 3D model, videos, or synthesis instructions. This supports students’ self-directed learning while reducing the cognitive load. Following the laws of figure-ground separation and closedness, the information elements are provided with a neutral, high-contrast background and a frame. Moreover, images that have a clear relation to the text are used [
30]. Not only because of the possibility of combining different media systems but also because of the better clarity, the AR is accessed by scanning the Zapcode on the analog life cycle document (
Figure 6).
The cycle title is already part of the first task since the inaccurate term bioplastic, often encountered in everyday life, is used here. Further, in the field of “Cultivation”, possible plants for obtaining biomass are discussed.
PLA was chosen as an example of a biobased, biodegradable plastic because, on the one hand, it is one of the few commonly produced and widely applicable bioplastics [
34]. On the other hand, the production takes little time (compared to, for example, plastics made from starch) and is feasible without unacceptable potential hazards [
35]. In the field of “Production”, the synthesis of a polymer is discussed using the example of polylactic acid (PLA). In an experiment, the students produce PLA themselves and should pay particular attention to the consistency or viscosity of the reactant and product. The viscosity change is to be explained using an animated three-dimensional AR model, which shows the dynamics of the particle level during the experiment or a step-growth polymerization (
Figure 6). Symbols and processes shown in the model are named or explained using an associated info text. In the “Use” field, the advantages of biobased, biodegradable plastics are demonstrated by employing various possible uses and further highlighted by considering the problems of exclusively biobased and fossil plastics. An excerpt from a report on an Indian landfill is used to illustrate the environmental and health issues associated with landfilling plastics [
36]. The advantages of biobased, biodegradable plastics, as shown in the previous fields, are leveled in the “degradation” field. The poor carbon footprint and the balancing act between the durability and degradability of a product made from PLA serve as arguments [
37,
38]. The use of entirely different materials and the elimination of plastics—using the example of the current packaging of an iPad [
33]—are presented as “alternatives to the alternative”. Because it cannot be assumed that the learners were familiar with packaging then and now, corresponding illustrations were added to the information box. This part of the station makes it possible to sensitize the students concerning the sustainable handling of “(plastic) waste” in accordance with the EU Waste Framework Directive [
39].
4.8. Debriefing
Following the processing of the learning scenario, a debriefing takes place with the learners. In this phase, the focus is on process-related assessment competence and technical language communication. In addition to individual results from sub-topic 1, the evaluation scales of the groups for the areas of country risk, concentration, demand, substitution possibilities, and recycling potential are transferred to the online tool “Oncoo”. Access to the tool is provided via a QR code. No registration or data protection critical transmission of personal data is necessary. If a criticality aspect shows widespread, individual deviations or even completely unexpected evaluations, a reason is requested, or the evaluations are discussed in plenary, and misunderstandings are clarified. In addition, the recycling potential and substitutability criteria are taken up in more detail by discussion questions such as “Does it make sense to replace fossil plastics with biobased plastics?” or “What is meant by a recycling-friendly product design?”. Subsequently, a link back to the initial question of the learning scenario and the socio-critical problem presented at the beginning is to be established. For this purpose, the learners are given an augmented worksheet containing a spider’s web diagram with six assessment categories for sustainability. With the help of their knowledge gained from the learning experience and the augmented information, the students are to assess the production quantity, the substitution potential of fossil plastics, the trade dependency, the risks for people and the environment in the production as well as in the disposal and recycling of plastics. Based on this, the students can reason on whether plastics should be used as materials for iPads (and more). This can be performed as part of a whole class discussion.
6. Limitations
A consistent pattern emerged despite the varying time allocated to different groups for the tasks. It is worth noting that not all groups were supervised by the same teacher but by their respective teachers, which has advantages and disadvantages. While the generalizability of the results is a definite advantage, the comparability of the findings might be affected due to uncontrollable factors. To obtain more general results, testing the learning scenario in different schools, grades and with more students would also be helpful. Nonetheless, the overall outcomes provide valuable insights and trends, and by working with different teachers, we were able to mitigate the influence of biases and research enthusiasm.
The survey did not directly inquire qualitatively about the most interesting aspect of the level of perceived understanding; instead, the responses were based on the students preferences and the feedback provided for improvement. More explicit questions in the future could be beneficial to achieve a clearer triangulation of the data, but they were not the primary focus of this case study. While we cannot fully control all influences, we are aware of this limitation and have tailored our approach to our target user group, reporting on a field study conducted in the school setting.
The quantitative data collection process was not optimized. Since there is no association between the completed questionnaires and the individuals at each station, reliable data imputation is not possible.
The shortening of the Rheinberg et al. questionnaire means that we no longer collect the entire construct of current motivation from Rheinberg et al. [
25]. However, we receive (time-efficient) feedback specific to our AR learning environment. Therefore, items also had to be specified, as the original items generally refer to “activity”. We adapted this specifically to obtain explicit feedback on the AR environment. The students stated that they understood the questions, so we assume that validity can be accepted.
7. Conclusions
The findings of this study provide further evidence that providing an appropriate amount of information and integrating learning content with relevant and engaging contexts through appropriate choice of medium, e.g., AR, can enhance students’ situational interest and motivation. The students expressed positive feedback regarding including critical aspects and the importance of learning autonomy and self-regulation, which they found beneficial. Additionally, they appreciated the clear instructions, appealing design, and meaningful integration of AR into the classroom, particularly in the context of plastics used in iPads.
Nevertheless, it is essential to acknowledge that there may be differing preferences and effects concerning the use of AR, which requires a more comprehensive investigation. Despite these findings, the study highlights the significance of tailoring educational approaches to meet individual student needs, incorporating engaging technologies, like AR, to create meaningful learning experiences and support students’ interests, motivation, and effective learning outcomes.