Introducing the object of learning in interaction: vocational teaching and learning in a plumbing workshop session

ABSTRACT In vocational education, the learning content is often considered as concrete and specific, and the vocational learning involves physical work and interactions between participants and artefacts. Furthermore, one teacher has the overall responsibility for several students during classes in the vocational workshop at school, which means that the teacher has limited time for every single student and that the few minutes they meet become very important. However, the documented knowledge about how vocational learning is constituted in the vocational classroom and what learning content is focused on in the interaction between teachers and students is very sparse. In this study, we focus on how the enacted object of learning and its critical aspects are made relevant, when a student and teacher in a plumbing workshop session negotiate the conducting of a task in Swedish vocational education. This will be done by using CAVTA (Conversation Analysis and Variation Theory Approach) to make a close and detailed analysis of video recordings of the interaction between the student and teacher when a task is introduced in the workshop session. The results show a complex process, where the teacher alternates between parts and wholeness, using several semiotic resources at hand when highlighting the learning content.


Introduction
In technical vocational education, the learning content of programmespecific subjects is to a great extent handled in the interaction between teachers, students and artefacts, and in relation to a practical doing (Andersson 2019;de Saint-georges and Filliettaz 2008;Filliettaz, Durand, and Trébert 2015;Sakai et al. 2014). Given that learning takes place in the interaction between participants and between participants and artefacts in their specific contexts, this interaction appears to be something that is important for vocational students' vocational learning trajectories. Vocational education in Sweden is conducted as a dual system, where one part is school based and one part is workplace based (Andersson and Köpsén 2018;Kilbrink and Bjurulf 2013). However, the vocational programmes are mainly school based, which makes the vocational learning at school an important part of vocational education in Sweden (cf. Andersson and Köpsén 2018;Berner 2010;Ferm et al. 2018;Kuczera and Jeon 2019). In the vocational workshops, the teacher is in charge of the learning content that is based on the syllabuses and sometimes also on their own judgements (Asghari 2017;Kilbrink et al. 2014). Nevertheless, there are currently few studies that focus on teaching and learning about specific subject content in vocational education where vocational teachers and students interact with each other and in relation to a practical doing in a teaching context within school (Berner 2010;Lucas, Spencer, and Claxton 2012;Schaap, Baartman, and de Bruijn 2012), not least in the area of technical vocational education, educating, for example, plumbers, welders or industrial workers (cf. Kilbrink and Bjurulf 2013;Kilbrink and Asplund 2018).
A common approach in teaching vocational workshop sessions is to start with a general introduction and then let the students engage in individual tasks, with the teacher going around giving the students individual feedback so that they can continue with their work (cf. Asplund and Kilbrink 2020;Besmond and Wood 2017;Gamble 2001). In vocational education in Sweden, it is also common that one teacher is responsible for several students achieving the goals of the vocational subject syllabuses during classes in the school's vocational workshop. It is also common that students in the same class work with several different tasks during the same session, which means that the teacher has to handle several objects of learning (cf Marton and Tsui 2004) simultaneously. The fact that the teacher is alone as an educator in these situations and has to handle up to 25 students at the same time, who can be spread out in several different rooms, means that the teacher has limited time to devote to the individual meetings with each student. According to Filliettaz, Durand, and Trébert (2015), the teacher, with his or her experience and specific professional knowledge, can support the students in their vocational learning in these kinds of meetings. This means, what happens during the limited time in which the teacher and each student meet during a vocational workshop lesson is very important in several aspects. Hence, these meetings are vitally important for teachers and students to develop a common starting point for -or a shared understanding of -what is to be learned, how it should be learned, and why (Asplund and Kilbrink 2020;Marton 2010;Kilbrink and Asplund 2018).
Research has also shown the importance of adapting the teaching to the students' level and that teachers are aware of students' knowledge and understanding in relation to the learning content, in order to be able to support them in their learning processes (cf. Asplund and Kilbrink 2020;Hattie 2008;Lo 2012;Marton 2015). However, as far as we know, there are few studies focusing on what learning content emerges and how it is enacted in interaction when a vocational teacher and students meet during a single workshop lesson. Overall, there is a lack of studies in vocational school contexts focusing on the vocational learning processes in relation to specific learning contents, and thus we know little about these complex processes (cf. Asplund and Kilbrink 2018;Berner 2010;Lucas, Spencer, and Claxton 2012), not least in the area of technical vocational education (cf. Kilbrink and Bjurulf 2013;Kilbrink and Asplund 2018). To meet this need for research, this article aims to explore the interaction that takes place in relation to the learning content when a student meets the teacher to discuss the conducting of a task at hand during a vocational workshop lesson/session at a Swedish upper secondary school. This will be done by conducting a close and detailed analysis of a teaching situation at a Sanitary, Heating and Property Maintenance Programme, which is one of the vocational educational programmes in Sweden aiming to educate future plumbers, based on the following research question: How is the enacted object of learning and its critical aspects made relevant in the interaction, when the student and teacher negotiate the conducting of a task that is introduced in the workshop lesson?

Previous research
Recently, there has been a greater interest within the research field of vocational education towards studying the interaction between students and vocational educators in teaching and learning situations. What these studies have in common is that they show the significance of the interaction for the students' vocational learning trajectories Kilbrink 2018, 2020;Kilbrink and Asplund 2018;Lindberg 2003;Schaap, Baartman, and de Bruijn 2012). Studies have been conducted within school-based settings as well as work-based settings, which are the two main learning pathways in vocational education (Andersson and Köpsén 2018;OECD 2009). Research done in workplace-based settings has among other things taken a closer look at the role of guidance and mentoring in vocational education and its significance to appreciators' vocational learning trajectories. For instance, De Saint-georges and Filliettaz (2008) examine the role of close guidance in vocational education and illustrate that instructing someone is very much an interactive process, and that when projecting a certain trajectory, the ambition is that the learner following that trajectory will be able to perform the task in an autonomous way. Through a close and detailed microanalysis of the interaction between learner and teacher, de Saint-Georges and Filliettaz also highlight the importance of engaging learners with their five senses in action. In another study, Filliettaz, Durand, and Trébert (2015) demonstrate the complexities in the vocational teaching and learning processes when mentors and students are 'doing guidance' in workplace settings, thus highlighting the importance of interactional competences for workers when doing guidance. Viewing guidance as an interactional accomplishment and not an abstract category, Filliettaz, Durand, and Trébert (2015) show that guidance is a complex process and that it can be dynamically combined and evolve in time when mentors and students are doing guidance. However, guidance is also, according to Filliettaz et al., to some degree, framed as invisible by participants themselves, which highlights the importance of interactional competences in vocational education.
A significant part of vocational education takes place within the school's domains, specifically in the Nordic countries but also in for example the Netherlands and Switzerland. Both students and teachers in Swedish technical vocational education emphasise the importance of school-based vocational learning as one part of the vocational education (Kilbrink et al. 2014. Research in vocational school settings that has a focus on the interaction between teacher, students and artefacts has handled issues related to vocational skills and competences (cf. Lindberg 2003Lindberg , 2019, students' identity work (Åberg and Hedlin 2015), and more general pedagogical issues (cf. Khaled et al. 2016;Kärner and Kögler 2016;Schaap, van der Schaaf, and de Bruijn 2017). Hämäläinen and Cattaneo (2015), for example, examine how emerging technology-enhanced learning settings in school settings in Finland and Switzerland mediate instructional activities when teacher and students interact. In another interaction study, highlighting the application of new technology in vocational education, Asplund and Kontio (2020) show how smartphones are used as happy objects in students' identity work and that these identity constructing processes intersect with the students' future vocational identities (see also Kontio and Asplund 2019).
With the exception of Asplund and Kontio (2020) and Kontio and Asplund (2019) above, there are few studies that have an explicit focus on the interaction per se, and that uses video recordings as a research method in vocational school workshops. When it comes to studies concerning the vocational content, there are even fewer studies that use such an approach. Besides the work of Asplund and Kilbrink, who highlight specific dimensions of vocational learning by emphasising how it is often taught in interaction between teacher and student and including an aspect of handicraft; a concrete doing and practical experience (cf. Kilbrink 2018, 2020;Kilbrink and Asplund 2018), two other studies could be mentioned.
In her study on assessment actions in Swedish floristry education, Gåfvles (2016) explores the interaction between teacher, student and flowers when assessing ongoing work and performance in a school context. Focusing on how this interaction influences and mediates what occupational aesthetics in a floristry educational context consist of, Gåfvels shows how vocational (floristry) knowing is displayed when the teacher encourages the student to visualise 'professional vision of flowers, traditions, and standards ' (2016, 147). Exactly what these occupational aesthetics consist of the study does not provide a full account of, however, thus Gåfvels is highlighting the need for further studies. Another study that takes place in a Swedish vocational educational context, and that explores the interaction between vocational teacher and students with an explicit focus on assessment is Öhman's study on feedback practices within ongoing teaching and learning situations in hairdressing education (2018). In her study, Öhman illustrates feedback as a problem solving, cooperative process, in which the tacit dimensions of hairdressers' knowing are made explicit through the fine-tuned coordination of communicative resources used by the teacher and the students in the interaction.
However, with the exception of these studies, there are few studies on classroom interaction within the field of vocational education that have a focus on how vocational learning is done in interaction in the vocational classroom/workshop, and what vocational learning content is made visible in the interaction between teacher and student, and thus made possible to learn. To study what is possible to learn during a lesson is a way of understanding why students learn, or do not learn what they are supposed to learn. Kullberg, Kempe, and Marton (2017) argue that 'research needs to take into account both what aspects are made possible to discern in a lesson, as well as how they are enacted in the interaction with the students' (567). Here we identify a need for studies that have an explicit focus on the specific learning content that is oriented towards and thus made visible in the interaction between teacher and students in vocational educational school settings. Our study should be seen as a contribution in that we go a step further and carry out in-depth studies on the specific learning process when a teacher interacts with a vocational student in relation to the specific vocational learning content in a plumbing context, during the short but crucial time they meet face-to-face during a vocational workshop lesson.

Context and data material
This study is conducted at a Swedish upper secondary school for vocational education. As mentioned above, vocational education in Sweden is mainly school based, although it includes both school-based and workplace-based learning (Andersson and Köpsén 2018;Kuczera and Jeon 2019). The current curriculum for upper secondary education was introduced in 2011 and it is called GY2011. The students at the vocational programmes study vocational subjects that are linked to the profession, as well as theoretical subjects such as Mathematics, Swedish and English. Based on GY2011, the students who are studying at vocational education programmes also have the opportunity to choose courses that make them eligible for university studies (Skolverket 2011). The vocational teachers are responsible for creating conditions for vocational learning for whole groups of students in the vocational classrooms/workshops, with limitations of tools, machines, space and materials, which by implication often makes it necessary to have several different tasks ongoing in the workshop at the same time. Thereby, the students can alternate between tasks in the workshop, depending on their needs and what equipment is available. The upper secondary school where we conducted our research is a municipal school, where a number of different upper secondary vocational programmes are offered. The Sanitary, Heating and Property Maintenance Programme is one of those programmes, which aims to educate future plumbers. The upper secondary school is located in a larger city in Sweden. Part of the education within the Sanitary, Heating and Property Maintenance Programme is carried out in the school's workshop, where our data material (video recordings) has been collected. The video recordings went on for a whole workshop session of 3 hours (180 minutes). At the beginning of the lesson, the vocational teacher had 10 students, but the number of students increased to 16 over time. For video recording purposes, we used two cameras; one camera recorded two focus students (one at a time) and the other camera recorded the vocational teacher and his meetings with the students during the lesson.
The school's workshop consisted of different small rooms where the students practised pulling pipes and worked with bathroom customisations, including installations of toilets, sinks, boilers and water heaters. The vocational teacher went from room to room to help students who had questions about their practical work. Every student worked with their own task, from a list of tasks to be done during the school year. The teacher kept track of what the students had done in relation to the tasks as well as the learning objectives in the vocational subject syllabuses by administrating a checklist. During class, the students were encouraged to find their own ways of solving various problems, before writing their names on a whiteboard working as a queue for getting help from the teacher. Different suggestions for problem solving were written on another whiteboard in the workshop -for example consulting a handbook or the Internet, asking a classmate or just trying a solution to see what happens. This was a way of encouraging the students to solve their own problems, both from a learning perspective (as problem-solving skills are important to develop to meet the demands of their future working life), and due to practical reasons -one teacher cannot answer every possible question from every student in the classroom due to time limitations. However, the short time when every single student actually got the teacher's attention, the interaction between them really needed to help the student further in his work -which made the quality of the meeting important. From previous research, we know little about what such a meeting contains in terms of teaching and learning, and how the teacher and student interact in relation to the learning content. Therefore, we aim to conduct a close and detailed analysis of the interaction in a meeting between a student and a teacher when a task is introduced to the student in the workshop session. In our observation, this meeting between the student and the teacher lasted for 3.45 minutes, and served as the basis for the student's continuous work. The meeting was initiated by the student's question about how to start his work with the task at hand. The analysis will be carried out based on the research question relating to how the enacted object of learning and its critical aspects are made relevant in the interaction.

Theoretical and methodological framework
The analysis was made on a micro-level based on CAVTA (described below). We watched the video recordings from the meeting between the student and teacher when a task was introduced in the workshop session several times -the researchers individually and also together as a group in several analysis meetings. The video data was transcribed in detail according to CAconventions (see Appendix). We have based the analysis only on what is done and made relevant in the chosen teaching situation in relation to the enacted object of learning, and are not aiming to interpret for example what the teacher aimed for or what the student actually learned. We are solely focusing on the interaction that takes shape, based on the research question and the theoretical framework CAVTA. We have informed the participants about the project and followed the ethical principles from the Swedish Research Council (Vetenskapsrådet 2017) and all participants have given their written consent to participate. The reported das have been anonymised.

CAVTA -Conversation Analysis and Variation Theory Approach
In this study, CAVTA (Conversation Analysis and Variation Theory Approach) serves as both a theoretical and methodological framework. CAVTA is a combination of Conversation Analysis (CA) (cf. Sahlström 2011) and Variation Theory of learning (cf. Lo 2012; Marton and Tsui 2004), adapted to a pedagogical setting where teacher(s) interact with student(s) in relation to different learning content (cf. Asplund and Kilbrink 2020;Kilbrink and Asplund 2018). By implication, we regard learning as a process that includes both an aspect of what is being learned and an aspect of how learning is done in interaction during the enacted teaching situation Emanuelsson and Sahlström 2008).
This study focuses on the interaction between a teacher and a student with a focus on what learning content is oriented to, and how this learning content is made relevant in a plumbing workshop session in the Sanitary, Heating and Property Maintenance Programme. In the following section, we describe the important aspects from the CA-approach and Variation Theory used in CAVTA, respectively.

CA -Conversation Analysis
CA deals with explaining the shared methods participants in interaction use in order to produce and recognise their own and each other's conduct. From a CA perspective, sense-making and understanding are constructed and co-constructed in and through the coordinated interaction of participants, and the interaction between participants and artefacts in specific social and cultural contexts. The process of CA should be undertaken within an emic approach (Duranti 1997). This means that talk-in-interaction should be viewed from the participants' perspective, with an aim to 'discover how participants understand and respond to one another in their turns at talk, with a central focus on how sequences of action are generated' (Hutchby and Wooffitt 1998, 94). Thus, analysis of the participants' 'own terms' (Schegloff 1997) is a methodological exhortation to ground interpretations with the ongoing turn-by-turn interaction. In identifying which actions the participants themselves make relevant and orient to at a specific point in the interaction, and to show this in a convincing way in the analysis, CA research has developed a 'proof procedure' method (Sacks, Schegloff, and Jefferson 1974), which takes into account the viewpoint of the participants. Such emic analysis involves the use of the participants' demonstrated interpretations of each other's actions in situ as a resource in the analysis and as a means of enabling readers to judge the claims of the analyst.
Through the increased use of video methodologies, CA has recently been interested in not only paying attention to verbal resources but also embodied aspects such as gesture, gaze, body posture, body movements and embodied manipulations of material objects (Goodwin 2000;Mondada 2016), which are seen as constitutive of and integral to the ongoing interaction. In line with this embodied turn (Nevile 2015), the relationship between verbal and embodied practices is seen as processes that mutually contextualise one another, providing public resources for participants in the interaction to organise relevant actions which, in concert with each other, contribute to the ongoing situated learning activity (Goodwin 2000(Goodwin , 2006. With an interest in capturing participants' talk and embodied practices, CA researchers have developed ways of representing these practices that capture the rich subtlety of their delivery (Hepburn and Bolden 2013). In this article, these practices will be presented in the form of detailed transcriptions of spoken data, as well as still images of visual phenomena in the interaction between the teacher and the students.

Variation Theory
The other theoretical basis for this study is the Variation Theory of learning. In this theoretical framework, there is a specific focus on the content of learning relating to the what-aspect of learning. To refer to the content of learning in Variation Theory, the concept object of learning is used. There can be a difference between what the teacher planned for (intended object of learning), what was possible to learn in the actual learning situation (the enacted object of learning) and what the students actually learned (the lived object of learning) (Marton and Tsui 2004). In this study, we focus solely on what was possible to learn in interaction in the learning situation, hence the enacted object of learning, and not what the teacher intended or what the students actually learned. Furthermore, the object of learning has a direct and an indirect aspect -referring to the content (direct aspect) and the ability of acting upon the content (indirect aspect) (ibid.). For example, there is a difference regarding the indirect aspect in understanding how to TIG-weld and to actually make a TIG-weld (cf. Asplund and Kilbrink 2020). The object of learning can be regarded as dynamic, and the interaction between the teacher and the learner can influence the enacted object of learning in the actual teaching situationhere and now Kilbrink and Asplund 2018;Lo 2012).
In the teaching situation, some things are foregrounded while other things remain more or less in the background (cf. Lo 2012; Lo and Chik 2016). Hence, it is important to foreground the aspects that are to be learned and to make sure that the same things are in the foreground for both teacher and student. In CAVTA, there is an important connection between the Variation Theory and the CA-approach, while the interaction can help the participants to reach a shared understanding of what is foregrounded. The aspects that need to be learned in order to know the object of learning are called critical aspects (Lo 2012;Marton and Tsui 2004), and those aspects can be highlighted in the teaching situation by using different patterns of variation. The critical feature of the critical aspect is when the aspect adopts a specific value. In this study, we focus on the critical aspect's right value as it emerges in interaction, specifying for example, when something is done in the right way (cf. Asplund and Kilbrink 2020). Variation Theory emphasises variation as crucial in order to discern the critical aspects and to help learners learn. In Variation Theory, there are different patterns of variation which can be a part of making learning possible: contrast, generalisation and fusion (cf. Kullberg, Kempe, and Marton 2017;Marton 2015). Contrast, as we use it in CAVTA, is when a critical aspect is compared to something it is not (for example, showing how far from the welding material you can hold a weld and comparing it to when you hold it too far away), generalisation is when different appearances of the critical feature of the critical aspects are made visible (for example, different possible ways of holding a weld when welding) and fusion is when more than one critical aspect are present at the same time (cf. Asplund and Kilbrink 2020). Lo and Chik (2016) also divide fusion in two horizons of fusion where one horizon concerns how the parts and the critical aspects of the object of learning relate to each other (internal horizon of fusion) and the other how the object of learning as a whole relates to its environment (external horizon of fusion).
What is in the foreground and what is in the background in the teaching can change during the situation, depending on the interaction between teacher and student (cf. Asplund and Kilbrink 2018). Therefore, in this study, we will analyse what objects of learning are focused on, and how they are oriented to in the interaction between student and teacher using CAVTA. Furthermore, in the analysis, we will also examine what critical aspects and critical features are highlighted in the interaction, how this is done and which patterns of variation are used to highlight those critical aspects and critical features of the object of learning.

Analysis and results
In this section, we carry out an in-depth analysis of the interaction between the vocational teacher (T) and a student (S) in a meeting where a task is introduced in the workshop session. The analysis is based on the analytical tools from CAVTA described above, which helps us see how the enacted object of learning and its critical aspects are made relevant in the interaction. This meeting between the teacher and the student is initiated by a question from the student. After the student has contacted the teacher in the workshop, they walk together through the workshop to the student's workplace. On arrival, the student says that he does not really know how to start his work and then he points down to several valve parts lying on the floor: Example 1 -It really should look like this In line 1, the student orients himself towards the valve parts lying on the floor, by asking if he should "put them together" while pointing at them with one hand. Here, the student proposes the object of learning to assemble the valve parts, where the indirect object of learning (the ability) is to assemble and the direct object of learning (the content itself) is the valve parts. However, the teacher does not follow up on the student's proposal. Instead, he draws attention to the wall where the student works (line 3), whereupon he encourages the student to follow him to a whiteboard that is mounted on a wall a few metres from the student's workplace. In line 5, the teacher then tells the student 'you should do this part' while pointing with a pointing stick at a drawing that covers large parts of the whiteboard. After a brief silence, the teacher says: 'it really should look like this just like this as on the drawing on your installation wall' (lines 8-9), and he thus shows where the parts come into the wholeness. At the same time, the teacher uses different forms of performance (the teacher compares what the student should do, with what it looks like in the drawing). This can be seen as generalisation as pattern of variation 15 (.) there you should connect cold to hot water (.) and so 16 0.8 it goes out (0.8) to a shower mixer (.) so ((brings the pointing 17 stick along the drawing)) ((inhales)) and the meaning, the aim 18 1.5) with (.) with the exercise itself e: the exercise is that you get (1.5) 19 ((inhals)) you should thus get e :: working with and getting these 20 eleven)) different valve parts in the correct order ((looks at the student)) 21 S: The student affirms the teacher with a shorter 'mm' and then the teacher, while pointing with a pointing stick at the drawing (lines 11-13), describes the cold water's way through three different valves (shut-off valve, check valve and safety valve) before it goes up in the hot water heater (lines 13-14). Afterwards, 'it comes out in a control valve' (line 14), and there the student, according to the teacher, should 'connect cold to hot water' (line 15) and then the water goes out in the shower mixer. After describing the water's way through the system, the teacher goes on to justify the purpose of the exercise, namely that the student "working with and getting these different valve parts in the correct order" (lines 19-20). Here, correct order becomes the critical aspect of the valve combination. The student follows the teacher's movements with the pointing stick on the board throughout this sequence, and when the teacher tells about the purpose of the exercise, their gazes meet, and the student again affirms the teacher with a shorter 'mm'.
The order of the valve parts (as a whole) is made an object of learning of the work with an installation wall (with a heater), that is the object of learning for the working task at hand, and the order of the individual valves emerges here as a critical aspect of this object of learning. In this way, a part of a larger whole is lifted out here for the student to focus on (valve parts in the drawing are separated out). In relation to this, the teacher varies the indirect object of learning (the ability) in the interaction, which here and now emerge as understanding the order of the valve parts by reading a drawing, in order to later being able to assemble the separate valve part in the correct order. The direct object of learning (content) is held constant in the example and it is about the order of the valve parts. As a whole, the order of the valves becomes a critical aspect of the superior object of learning, to work with an installation wall, and when they have their correct intermutual order, the critical aspect has adopted the correct value, that is the critical feature (cf. Lo 2012; Marton and Tsui 2004).
In lines 22-23, the teacher explains to the student that it is important that the valves come in the correct order, and in lines 24-26 the teacher exemplifies a situation where two of the valves come in the wrong order (contrast as pattern of variation). The teacher thus contrasts a fictitious situation where the valves come in the wrong order with that they must come in the correct order. 'Then it won't be good' says the teacher (line 28) and he gets affirmation from the student. The intermutual order of these two valves is oriented to as a critical aspect of the object of learning that deals with the order of the valves as a whole. The sequence ends with the teacher telling what would happen in the fictional situation presented, namely, that the safety valve would lose its function, which enhances the contrast in explaining what it is, that would not be good.
In the next example below, the teacher and the student have moved back to the workplace where there is a hot water heater mounted on the installation wall. The example begins with a rather long teaching turn where the teacher, again, and just as in Example 1, describes the way of water through the system. This time, the teacher's instruction takes place through an orientation towards the hot water heater itself, and the valve combination that is mounted just below the heater: the wall, turns to the student)) proficiency about (look at 39 eleven)) the water heater)) how it works ((looks at student)) 40 S: um um 41 (.) 42 T: then we will build our own 43 S: a: a: At the beginning of the turn, the teacher orients himself towards the valves as a topicalised resource for establishing the action as related to what they were talking about previously (see Example 1), and he then clarifies that the valves here are assembled 'in a single valve piece' (lines 31-32), which is called 'valve combination' (line 33). Furthermore, in line 33, the teacher repeats the movement of water through the system, and this time he also calls the various valve parts by their name (lines 34-36). This time, however, the control valve is not mentioned as the fourth in the order (see Example 1), but instead the teacher says that there is a 'mixing valve' (line 36) after the 'safety valve' (line 35). By saying 'we call this' (line 32) and then listing the names of the different valve parts, the concepts are made (i.e. valve combination and correct valve names) into a parallel object of learning (the concepts of the parts with which the students is working).
In the same way, as in the previous example (Example 1), the teacher then completes the instruction of the cold water movement through the system by providing a motivation for the exercise, namely, that the student should get 'knowledge and proficiency about' (lines 37-38) how the hot water heater 'works' (line 39), 'we will build our own' (line 42).
In this sequence, the indirect object of learning (knowledge and proficiency about how the completed valve combination in the hot water heater works and to build his own valve combination) is linked to the direct object of learning -the order of the valves in the valve combination. The order of the valves is consistently the same in the two examples, but the forms of appearance are varied from the drawing on the board (Example 1) to the pre-assembled and to the assembled parts (Example 2). Hence, the order of the valve parts, as a critical aspect of the work with the installation wall (the superior object of learning) is highlighted in different ways (by using different semiotic resources) to the student by using generalisation as pattern of variation. In this example (Example 2), the teacher also emphasises the concepts of the different parts more clearly.
Immediately after the teacher and the student have oriented themselves to the valve combination on the hot water heater, the teacher turns his attention to a cardboard box on the floor in which there is a valve piece, in which the valve parts are already screwed together.

Example 3: Remember how it looks
In the example, the teacher orients himself towards a valve piece that is in a smaller carton on the floor, while he tells the student that his task is to unscrew the piece 'completely' (line 50). Then, the teacher follows it all up by first saying that the valve piece consists of 'three different parts' (line 51) and then he lists them; 'shut-off valve, check valve and safety valve' (line 52). In line 55, the teacher repeats that the student should unscrew the piece 'completely', and then he says, while laughing and smiling at the student, that he should 'remember what it looks like' (line 57) because he (the student) is going to screw it back together again. Here, the teacher makes it relevant for the student to be able to discern the critical aspect what the valve combination looks like, so that when he screws back it again, he can simultaneously remember and be able to perform screwing them together based on what they looked like when he disassembled them.
In the example, the teacher thus highlights the first three valves in the valve piece, while the fourth valve (control valve/mixing valve), which was oriented in the previous example, is not mentioned at all. The student affirms the teacher's comment by saying 'yeah' in line 60 while smiling and looking up at the teacher. The example then ends when the teacher first says that it is 'some unnecessary work' (line 61), but shortly thereafter justifies why the student should disassemble the valve piece: 'because you should get the opportunity to screw it yourself' (line 64), whereupon he hands over the valve piece to the student.
In this sequence, the teacher clarifies to the student that the student has a task that is about unscrewing the valves. The task is for the student to learn how to screw the valves back together by remembering how they were before. Still, the direct object of learning (order of the valves) is consistently the same, but the indirect object of learning varies, which makes all three examples as a whole an example of how different semiotic resources can be used to show the same critical aspect (the order of the valve parts) of the superior object of learning (to work with the installation wall). This means in the CAVTA analysis that the teacher used generalisation as pattern of variation.

Discussion
As the school-based part of the subject-specific Swedish vocational education serves an important part in students' vocational learning (cf. Andersson and Köpsén 2018;Berner 2010;Ferm et al. 2018;Kuczera and Jeon 2019), we need to know more about learning processes in vocational workshop and how the learning is done in interaction between teachers and students in relation to specific objects of learning (cf. Asplund and Kilbrink 2018). In this article, we have studied the interaction between a teacher and a student with a focus on what learning content is oriented to, and how this is done when the student and teacher negotiate the conducting of the task introduced in the workshop lesson. Just like in Gåfvels (2016) and Öhman's (2018) research, we get more in-depth knowledge in the teaching and learning processes that take shape in the interaction between teacher and student in the school-based vocational classroom in Sweden. However, this study complements those earlier studies by focusing on another vocational area -the Sanitary, Heating and Property Maintenance Programme, where there is a lack of studies. Furthermore, this study focuses on both what-and how-aspects of learning by combining CA and Variation Theory in CAVTA in the analysis process. This study also responds to Kullberg, et al.'s (2017) request for studies focusing on those aspects in relation to what aspects are made possible to learn and how those aspects are enacted in a lesson -which in this specific study is a plumbing workshop lesson/session.
Based on CAVTA (Asplund and Kilbrink 2020;Kilbrink and Asplund 2018), the analysis has been divided into three parts (Examples 1-3), based on how the teacher orients to, and uses the surrounding physical context as semiotic resources (cf. Bezemer and Kress 2016;Goodwin 2000;Nevile et al. 2014) in his teaching, when instructing the student about the task ahead, and as a response to the student's question about how to begin his work. In Example 1, the teacher physically moves the teaching from the student's workplace and orients to the whiteboard and the drawing of the closed water system on it, which is what the student is working on. At an early stage, it becomes clear that the teacher is highlighting the order of the valve parts, as the focus of the student's next task in the work with the installation wall (an order that will become central through the entire teaching session). In the CAVTA analysis (cf. Kilbrink 2018, 2020;Kilbrink and Asplund 2018), we can see how the object of learning is dynamic Kilbrink and Asplund 2018;Lo 2012) and that parts and wholeness are alternated and made visible in the interaction between the student and teacher (cf. Gamble 2001;Lo and Chik 2016). In this analysed section, one critical aspect of the work with the installation wall (which is the superior object of learning) is highlighted and emerge as the object of learning for the task at hand in this teaching session. By separating this critical aspect of the work with the installation wall, the teacher breaks down the student's work in smaller parts. Furthermore, the teacher opens up for the student to understand where in the wholeness the part becomes relevant (external horizon of fusion; see Lo and Chik 2016), by focusing the critical aspect the order of the valve parts on the drawing on the whiteboard, as a part of the entire installation wall.
The critical aspect the order of the valve parts is thus, from now on, oriented to and highlighted as the object of learning of the task, i.e. to assemble the valves in the correct order, with the intermutual order of the valves as a critical aspect (i.e. something that is important in order to be able to put the valve parts together in the correct order). The teacher then goes to the preassembled hot water heater (Example 2), which is fixed on another installation wall. He repeats the same procedure in his instruction and he shows where the valve combination should sit in relation to the valve combination as a whole, before he highlights the different valve parts' intermutual order. Finally, the teacher brings the teaching back to the student's workplace where the student asked his initial question and repeats the procedure once again -this time by orienting himself towards the valve parts on the floor, which the student will work on.
A pattern that emerges in the teacher's way of teaching is that each example as a whole becomes an example of the order of the valve parts. This order is highlighted by the teacher -and thus repeated -in different contexts in which he uses different semiotic resources (not only speech, body and gaze but also the material resources such as the drawing on the whiteboard, the preassembled hot water heater, and the working material available in the vocational workshop). Thereby, each context is an example of the same critical aspect (the order of the valve parts) of the work with the installation wall (the superior object of learning), which in the analysis can be seen as generalisation as the pattern of variation (different ways of showing the same thing, cf. Marton and Tsui 2004).
In his teaching, the teacher thus also repeats the object of learning (for the task at hand) to put the valves in the right order -in relation to the whole -which illustrates a dynamic movement that is constantly present and made visible in the teacher's teaching; the movement between part and whole and how they interact with each other (which can be related to external and internal horizons of fusion, Lo and Chik 2016). According to Lo and Chik, it is necessary to connect the object of learning to the wider context, to understand it more fully. Therefore, we must try to relate the object of learning and its critical features to the whole or context of which it is a part. The more dimensions of variation we consider, the more we can understand an object of learning in depth, and hence, the more powerful the learning experience. Thus, the enacted object of learning in this analysed teaching section is both made visible by variation of the critical aspects and by alternating between parts and wholeness, which, based on Variation Theory (cf. Lo and Chik 2016;Marton 2015), creates possibilities for learning. The motives for the task are also highlighted by the teacher in all three examples -and once again the part and the whole, and how they interact with each other, is oriented to by the teacher in that he motivates the task with the parts by putting them in relation to the whole. Given the teacher's teaching, it is also quite possible to, on the basis of CAVTA, relate to the didactic questions what and how (cf. Marton 2015), that emerge in the interaction. Through the three examples the direct object of learning (the content itself) is the same throughout (the valves in the right order as a part of the installation wall) while the indirect object of learning (the ability) varies in relation to the teacher's use of different semiotic resources: Example 1: The student should be able to see and understand, and be able to put together the valves in the right order Example 2: The student should get knowledge about how the completed valve combination in the hot water heater works and based on this build his own valve combination with the valves in the right order Example 3: The student must unscrew, remember and screw together the valves in the right order In parallel with the central object of learning for this task, the connection between cold and hot water is highlighted as a critical aspect. However, it is mentioned briefly but is not focused on further in the specific situation. In parallel with the teaching of the central object of learning, a parallel process emerges, in which the teacher continuously, and through the simultaneous use of different semiotic resources, informs the student about the concepts of the material to be worked on.
As de Saint-georges and Filliettaz (2008) and Filliettaz, Durand, and Trébert (2015) show that vocational teaching in a workplace setting includes an ambition of instructing the learner to be able to perform the task in an autonomous way in the learning trajectory, the teacher in this study supports the student with a lot of instructions, thereby also supporting the student's further autonomous conducting of the learning task in the vocational workshop at school. The approach taken in this article and the specific focus on the interaction that takes shape when a vocational teacher and a student negotiate the conducting of the task, which was introduced in the workshop lesson at school, shows the complexity of the teaching in this context, which we have little insight in and knowledge about in previous research. In this short session, it is the teacher who positions himself as the teacher and the more knowledgeable and the student positions himself as a student who wants to learn what he does not know and not yet can do (Sahlström 2012). This can be interpreted as a situation in which the teacher and student together and socially construct a pact of learning, which Marton (2010) describes as one of two essential factors for learning. The other factor concerns learning content (the object of learning) being highlighted for the student in a way that makes learning possible. In order to do that, the critical aspects of the object of learning must be made visible (the student must be able to discern variation) in the teaching and learning situation Marton and Tsui 2004). In the analysed teaching situation, we can see that the teacher uses several semiotic resources simultaneously in his work to accomplish this. In his work with making the object of learning visible for the student, he verbally delivers a lot of information concerning the object of learning and its critical aspects. The verbal information is accompanied by the other surrounding semiotic resources; however, he does not give the student any opportunity to openly display his understanding of the task (which he for example could have done by inviting the student more actively in the conversation (cf. Asplund and Kilbrink 2020;Sahlström 2012). Thereby the teacher cannot be certain if, or if not, a mutual understanding of the learning content is accomplished (Melander and Sahlström 2010). Given the importance of establishing a shared and mutual understanding of the student's understanding of the object of learning (cf. Asplund and Kilbrink 2020;Hattie 2008;Marton and Tsui 2004;Sahlström 2011) this is something that could be further elaborated on. The lack of student participation in the interaction that takes shape might also in various ways reflect the relatively strong schooling role and limited workplace learning of the Swedish vocational education system. Considering the responsibility that rests on teachers' shoulders in the Swedish system to create situations similar to workplace situations in school settings, as well as the limited time to devote to individual instruction and limited access to resources for doing this, it is not that surprising that the teacher delivers a lot of information and highlights several aspects concerning what the students are supposed to learn, with the ambition to instruct each student to be able to perform the task in an autonomous way in the learning trajectory. However, one might argue for an approach that -despite these circumstances -could open up for the students to ask more questions about the task ahead (cf. Asplund and Kilbrink 2020;Ferm et al. 2018), and/or create situations in which students could be more actively involved with their senses in the learning process. As Filliettaz and colleagues (de Saint-georges and Filliettaz 2008;Filliettaz, Durand, and Trébert 2015) have shown in their work, instructing someone in a vocational education setting is a very complex process and engaging students with their five senses in action could be a strategy that would enhance students' vocational learning (see also Gamble 2001). But altogether, this study also highlights the importance of interactional competences in vocational workshop lessons.

Conclusion
By analysing the interaction that takes shape when the teacher and student interact in relation to the learning content, this study could contribute to initiating a discussion about how to teach and learn in relation to a specific vocational content in the vocational workshop. Highlighting how the enacted object of learning and its critical aspects are made relevant in the interaction, the result shows that the teacher uses several different semiotic resources (Goodwin 2000) at hand; speech, embodied resources, and a wide range of objects, such as the whiteboard drawing, the mounted water heater, and the physical valve pieces. The teacher uses generalisation as the pattern of variation (cf. Lo 2012; Marton and Tsui 2004), by moving between different physical places in the workshop -showing the same critical aspect (the valves in the right order as a part of the installation wall). Furthermore, the teacher alternates between parts and wholeness, which puts the task into a wider context. All these aspects together show how the enacted object of learning is made visible to the student in the interaction, thus creating conditions for learning. However, there was very little room for the student in the interaction, which makes it hard for the teacher to know if the student has understood the object of learning as intended. By involving the student to a higher extent in the interaction, the teacher could create better conditions for a mutual understanding of the object of learning. However, in order to be able to argue how to improve teaching and learning in the area of technical vocational education, we first need to gain more knowledge about the complex processes of vocational teaching and learning in more school settings as well as in more vocational areas. Therefore, there is a need to conduct more studies in the research area of actual teaching and learning in the vocational workshop.