The TPACK model/framework (otherwise known as the TPCK model)1 stands for the ‘technology, pedagogy and content knowledge’ model. The model was introduced by Mishra and Koehler (2006) following the insights of Shulman (1986a, 1986b), who in the 1980s had invented the PCK (Pedagogical Content Knowledge) model. The PCK model advocated the need to consider the intersection between pedagogy and content knowledge and train teachers accordingly. The TPACK model follows in the footsteps of the PCK model and advocates the need to consider the intersections between TPACK in order to effectively train 21st century teachers (Koehler and Mishra 2005, 2008; Koehler, Mishra, and Yahya 2007; Mishra and Koehler 2005).

The TPACK model has witnessed enormous success. It would be beyond the scope of this paper to account for all the various implementations, interpretations and developments it has fostered in only a decade. As of June 2013, Mendele (2013) listed 466 academic papers on the TPACK model. A good literature review can be found in Voogt et al. (2013).

Among the various trends of research that stem from the TPACK model, the one of specific interest to this paper discusses the interrelation between the TPACK components, arguing in favour, or against, the relative independence of each ingredient. As Voogt et al. (2012) point out, three different understandings of the TPACK model as a concept have been developed: TPACK as an extension of PCK (Cox and Graham 2009; Niess 2005), TPACK as a unique body of knowledge (Angeli and Valanides 2009; Archambault and Barnett 2010) and TPACK as the interplay of three different knowledge domains (Graham 2011; Koehler and Mishra’ 2005, 2008, 2009, Koehler, Mishra and Yahya 2007). In the first case, TPACK is seen as the integration of subject matter knowledge with technology, teaching and learning knowledge (Niess 2005, p. 510). In other words, TPACK is considered to be an evolution of PCK (Cox and Graham 2009). The integration of these three domains is interpreted as a way to teach using technology (Voogt et al. 2012). In the second understanding, what may be defined as a transformative view of the TPACK model is adopted. For example, Angeli and Valanides (2009) argue in favour of TPACK as a distinct body of knowledge that can be developed and evaluated on its own. In the third understanding, Mishra and Koehler put forth a different interpretation. They see TPACK not as an enhancement of PCK nor as a distinct body of knowledge but rather as a progressive understanding of TK (Technological Knowledge), PK (Pedagogical Knowledge) and CK (Content Knowledge) and all their intersections, leading to seven distinct bodies of knowledge (Koehler and Mishra 2008). Cox and Graham (2009) and Niess (2011) underpin the difficulties that such a conceptualisation, with its seven intersections, brings about. The model is further complicated by the fact that context is added by Koehler and Mishra as a fundamental part of the framework, as an element requiring deep understanding on the teacher's side. Koehler and Mishra's position can be defined as an integrative view of TPACK.

With respect to the integrative view of TPACK, it can be observed that the description of an educational experience can address different aspects, including how it was devised, how it was implemented, what was important when it was conceived and what surfaced as important after completion. In addition, the interplay between the different components of the TPACK model can have several interpretations. A teacher, for example, may start with the idea of using tool ‘t’ and then decide that for her goal the best pedagogical approach is approach ‘p’. Once the educational experience is made available in a public portal (such as the one presented in this paper), it may happen that another teacher takes a different path. Investigating experiences with approach ‘p’, he/she may be led to take tool ‘t’ into consideration. In other words, a good educational portal should be able to support several different conceptual pathways, possibly ones not even corresponding to the original goal of the teacher who created the experience in the first place.

In the mid-1990s, relatively simple learning objects were made available informally as instructors shared syllabi, lesson plans and learning activities. Later, more complex and/or topic-specific repositories came into existence as museums, journals and magazines, educational television productions and other actors placed content on the Web and encouraged it to be used for educational purposes. Many institutions developed learning activities around the objects (thus creating larger, ‘second-order’ learning objects) and made them available from their websites.

Afterwards, websites became populated by learning objects from all disciplines but, instead of housing the objects on their own servers, they often linked them to the original sites where the resources were made available. Large repositories of learning objects are now available on sites such as MERLOT (Schell and Burns 2011), a leading archive for higher education that provides tools for user comments and peer reviews; CAREO (Neven and Duval 2012), a collection of Web-based multidisciplinary teaching materials; and Wisc-Online, which houses the online resources supporting Wisconsin's technical colleges.

Examples of repositories of learning objects for use in specialised training include those from the aviation industry for which the Aviation Industry Computer-based Training Committee helped in setting standards. Another repository is the (NMC, 2007) Learning Object Initiative, thanks to which many industry and military issues have been resolved. Other early examples in this area include the Educational Object Economy (Roschelle et al. 1999) and Ariadne (Forte et al. 1997). More recently, spurred by the development of the ‘learning object metadata’ standard of the IEEE Learning Technology Standards Committee (LTSC), numerous initiatives have been launched in academic and corporate contexts (Neven and Duval 2012; Primo, Vicari, and Bernardi 2012). Several standards have also been developed in the field of e-learning systems (ELS) as reported by Cos Garcia (2011).

Learning object repositories can be difficult to navigate, and the educational material difficult to integrate into online courses. Schoonenboom, Sligte, and Kliphuis (2009) observe that the literature on the reuse of learning materials has largely focused on the development of materials. The authors developed guidelines that support staff and/or management in cases of (un)successful reuse of existing digital materials and provided methods for teachers in higher education in such cases. They collected existing strategies from 11 literature studies and developed new guidelines from 19 (mainly Dutch) case studies. Lukasiak et al. (2005) present the Smart Learning Design Framework that supports sharing, reuse and adaptation of learning material via a metadata-driven philosophy enabling the technicalities of the system to be imperceptible to the author and consumer. The system proposes the use of pedagogically focused metadata to support and guide the author and to adapt and deliver the content to the targeted consumer. Even though many educational technologies and services have been provided to enhance educational pedagogy, in contrast with what was expected, a drop in participants and subscribers to these educational technology resources among students and instructors was recorded in many different studies (Cuthrell and Lyon 2007; Jones 2009; Willems 2007). These studies have also identified that the reason for such a drop was that a ‘one-size-fits-all’ approach was used instead of an approach that provided educational courseware for students using all available educational technologies (Cuthrell and Lyon 2007; Matar, Khwaldeh, and Hunaiti 2007). Many adaptive ELS were created to satisfy students’ needs and learning styles using different approaches, but their focus and intent was not on unified learning object repositories (Aroyo, Mizoguchi, and Tzolov 2003; Dolog et al. 2004). Andrew, Farrow, and Cooper (2012) argue that online resources for education not only offer opportunities for those with disabilities but also raise challenges regarding how to best adjust resources to accommodate accessibility. The authors carried out a study within the EU4ALL (European Unified Approach for Accessible Lifelong Learning) EU-funded accessibility project at the Open University, United Kingdom, in parallel with studies at three other European universities, developing systems and services to give personalised access to online materials that include alternatives.

To overcome these limits, unified E-learning repositories (UER) were used for simplifying the tasks of sharing learning contents and resources between different universities through a unified access point. Such systems are capable of providing management information regarding contents and users; in addition, they give instructors and course authors the ability to reuse learning contents and to assemble them into courses (Hatala et al. 2007). Different initiatives have been implemented to support the idea of UER among organisations and educational institutions. The first one is called the centralised LCMS (Learning Content Management System) approach, where a central LMS (learning management system) is used to provide the shared courses as ready-made packages that can be used by instructors (Matar, Khwaldeh, and Hunaiti 2007). Such an approach can be performed using any available LMS such as Moodle, ATutor, Blackboard and WebCT. The second one is called the networked approach (NA). The focus of NA is on the learning objects level rather than on ready-made courses, so that each instructor can use learning objects and structure them into courses (Pouyioutas and Poveda 2005). An example of such a system is the learning object network with CAPA. (LON-CAPA, 2013) provides unified e-learning through a dedicated network; in order for universities to use the system, they should structure their servers to be a part of the learning network. LIONSHARE is another UER-oriented platform that uses NA for sharing resources between learners. SPLASH is an NA-oriented system that is actually used as a distributed learning objects repository/metadata tagging tool. SPLASH was developed as a part of the Portal for Online Objects in Learning (POOL) project, which is a consortium of several educational private and public sector organisations aimed at developing an infrastructure for learning object repositories (Perkins 1995). POOL addresses the issues of building such architectures including metadata, software and hardware, and bootstrapping the system with initial content. It also makes tools available for download to help set up similar infrastructures elsewhere and to connect them to POOL.

The authors observe that the tendency of current repositories is to retain content in the form of a broad mix of text documents, videos, audio files and graphics (EDRENE 2009). It also emerges that a few repositories include non-digital materials (e.g. text books). A little less than a third of repositories surveyed have a mix between free and commercial material. What is relatively clear is that educational repositories are mainly created to share learning objects, often characterised by metadata or ready-made courses, intended as an organised set of learning resources related to a specific discipline. However, they largely fail to provide a whole, fully described and reproducible learning experience that can clarify when, where and how materials, digital or not, were used; how the learning process was organised; what educational goals were planned; which educational benefits were generated and what the role of the technology was.

In order to schematise and understand the circumstances and the outcomes around an educational experience, studies have been conducted and conceptual and meta-learning frameworks have been proposed. The study in So (2012) endeavours to understand how teachers make use of online resources to design learning environments that are motivating and cognitively engaging to their learners. The final aim is to propose a resource-based e-learning environment (RBeLEs) framework, based on five teachers’ authentic experiences in planning, designing, implementing and reflecting on such learning environments. In-depth interviews were conducted to collect more information. In-depth interviews have the primary advantage of providing much more detailed information than other data collection methods such as questionnaires, and they are particularly useful when detailed information about a person's thoughts and behaviours is wanted (Boyce and Neale 2006). The five participating teachers were individually interviewed face-to-face for about 30 minutes before and after lesson implementation. All interviews were semi-structured, audio-recorded, and transcribed. In the pre-lesson interviews, the teachers were encouraged to describe how they had created the teaching designs and how they had planned to implement them in the classroom. The post-lesson interviews, in contrast, focused on understanding how the teaching designs were actually implemented, and what the pupils’ motivations and cognitive engagements were in the lessons.

Frameworks for supporting knowledge capture at source (Verhaart 2002) and collaborative knowledge management systems (Maher and Kourik 2008; Nunamaker 2001) have been proposed in different fields, for example in e-Government (Zhou 2008). The need to assess quality levels in engineering educational programmes led ABET (Accreditation Board for Engineering and Technology) to issue the Engineering Criteria 2000 (EC2000) standard (Lattuca et al. 2006). EC2000 shifted the basis for accreditation from inputs, such as what is taught, to outputs, what is learned. The new criteria specify 11 learning outcomes and require programs to assess and demonstrate their students’ achievement in each of those areas. In Besterfield-Sacre et al. (2000), a framework based on Bloom's taxonomy (Bloom et al. 1956) has been developed for better specifying the EC2000 outcomes. Bloom's taxonomy is based on six levels of the cognitive domain: knowledge, comprehension, application, analysis, synthesis, and evaluation. To meet EC2000 assessment criteria, information from all university constituents needs to be routinely collected and tracked longitudinally. The management of EC2000-related information through a data warehousing approach is the main focus of Ingham (2000); the data warehouse approach allowed the management of 100,000 student records covering a 10-year span, as well as 30,000 course records over a similar period of time. This has also led to the advantage of supporting the assessment process.

The OER is Florida's digital repository for instructional resources. It provides an environment for educators to search for, use, remix, share and contribute educational resources. The repository can also import resources directly from existing LMSs (e.g., Blackboard, Desire 2 Learn, Canvas). The diverse collections available for searching contain a wide range of resources, including open textbooks. Resources are free for educational use but may be protected through various copyright statements associated with each resource. The main audience of the repository is Florida public higher education faculty and staff, but Florida K-12 educators, educators outside of Florida, and guests can also contribute resources.

A growing number of repositories explicitly meant for students and families are becoming available for all levels of schooling. The Khan Academy (KHAN) is a not-for-profit organisation with the goal of bringing innovation to education by providing online materials and resources available free of charge for anyone, anywhere. Students can make use of an extensive video library, interactive challenges and assessments from any computer with access to the Web. Coaches, parents and teachers can have different levels of visibility regarding what their students are learning and doing with the Khan Academy resources. The BrainPOP repository (BrainPOP) encompasses more than 650 curricular topics designed to actively engage students from grades 3 and up. It creates animated, curriculum-based content that supports educators and students in school, at home, and on mobile devices. Resources include movies, quizzes, games, mobile apps, experiments, activity pages and other kinds of learning content covering hundreds of topics within math, science, social studies, English, technology, arts and music and health. All content is aligned to and searchable by US state standards, including Common Core State Standards. PoliLab Kids (PoliLab, 2013) is an Italian initiative that released an online repository of educational videos (lasting 2–3 minutes each) related to various areas (science, math, technology, etc.). Each video is accompanied by a rich set of educational materials including quizzes and a teacher and parents’ guide.

With the aim of driving and supporting the implementation of innovative technological experience at school, a number of technological and conceptual frameworks have been proposed (Bucciero et al. 2011; Di Blas et al. 2012; Vergallo 2012). However, they do not include a sharing platform like a repository, so they lack structuring of the material that is aimed to make it easier to share and reuse the experience. Also, it is evident that adopting well-designed collaboration process models (Barchetti et al. 2011) for supporting empirical research about the role of Information and Communication Technologies (ICT) and its influence on pedagogy-related concepts (various kinds of implementations, inclusion problems and solutions, envisioned benefits, etc.) could ease information-intensive research activities and improve results. Starting from these considerations, we defined the main requirements of the repository's collaboration and data model as will be described in the next section.

A scholar is investigating the relation between different kinds of group work in digital storytelling activities and the educational benefits achieved by the participants. She accesses a portal where hundreds of educational experiences are gathered. Each educational experience is accompanied by a rich set of materials (documents, presentations, videos, etc.) and is classified according to a set of 30 facets (technology used, benefits, organisation, inclusion issues, etc.) and a high number of facet values (for the facet ‘benefits’, cognitive benefits, relational benefits, etc.). First of all, she selects ‘digital storytelling’ as a technology-based activity. Then, she selects all the kinds of group work (there are four: homogenous, heterogeneous, same-skill and different skill group work) within the facet about organisation. She thus creates S1, a subset including all experiences that combine storytelling with all kinds of group work. S1 shows that digital storytelling and group work generate a number of benefits, among which relational benefits stand out as prominent. She now wonders whether this activity (digital storytelling implemented through group work) may have an impact on inclusion issues, but she wants to leave aside disability since she is not an expert in that field. She just wants to focus on disaffected students, immigrants and students with a poor background. She thus gets to the facet ‘inclusion issues’ and excludes ‘disabilities’. She gets S2, another useful subset that she saves for further investigation.

A high-school teacher in humanities wants to improve her use of ICT at school, and therefore accesses a portal like the one described above. First, the teacher browses the initial set (S0). She takes a look at the facet about technology, getting an idea of what technologies are most popular. She also takes a look at the ‘organisation’ facet, to see what kinds of pedagogical implementations (heterogeneous group-work, role-play, etc.) are used. Then she selects interactive whiteboards and tablets within the facet about technology (creating subset S1). She has an interactive whiteboard in her class but she seldom uses it. Moreover, she has been told that the school principal will buy a tablet for each student, so she needs to get prepared for this change. She further refines her exploration by selecting ‘motivational benefits’ within the facet about benefits and ‘group-work’ within the facet about organisation (creating subset S2). There are many disaffected students in her class, so it may be a good idea to start trying to involve them by getting the help of the performing students. Now, she notices with dismay that in S2, technical disciplines are overrepresented. Therefore, she goes back to S1 and adds the criterion that humanities be the overall discipline. She also excludes ‘immigrants’ as a problem within the facet about inclusion issues (in the profile of S1 ‘immigrants’ is a major issue, but there are none in her class). She gets S3, a small, interesting set. She saves the contents to investigate them at a later time.

In order to support the aims of the project exemplified by the above scenarios, two developments were needed:

A repository: to collect (in an organised fashion) all the materials available for each experience, along with managerial information (dates, who the author is, etc.). Users are the staff of the project.

Although they share a fair amount of information, the repository and the portal (given the different aims and the different types of users) required different design concepts and different implementation strategies that are described in what follows.

The objects stored in the repository were not simple files or learning contents but instead were educational experiences. From a technical perspective, an experience is a collection of resources (files and descriptions) related to the implementation of a technology-based activity at school. The experience data model defines the type, number and structure of such resources within an experience (see Figure 2).

A large variety of materials can be associated with an experience:

Interview(s): audio file(s) of interviews of the teacher (before and after the experience).

Each interviewer had to manage the lifecycle of the experiences assigned to him or her within the repository. A minimal set of metadata (for each of the objects) was added both for fast identification and for managing purposes. So, it was easy to find items such as what was done on a given day, how many interviews the repository held, which FEE forms were missing and what the job done by a specific interviewer was.

The collection and sharing of educational experiences consisted of four sub-processes: interview, review, tagging and publishing (see Figure 3). There were two types of interviews, one about expectations and one about results. The ‘expectation interview’ was taken before the educational experience began to investigate what the teacher was looking for. The ‘results interview’ was taken after the educational experience was completed. The audio of the interviews was recorded, then a transcript was made and the writing was tightened to eliminate what was not relevant. After that, the three FEE forms were filled in: expectation, results and a comparison between the two. Next, the editor reviewed all the materials and tagged the experience, interpreting the main findings of the FEE forms.

Flexibility in implementation was a key requirement, since the repository actually underwent a continuous cycle of design–implementation–evaluation–redesign as the project moved on and new needs surfaced. Alfresco Enterprise Content Management (ECM) software (Alfresco software 2013) was selected. The key technical features driving this choice were the following:

Alfresco is a lead ECM platform, widely adopted by both private enterprises and public corporations. Since the first release in 2005, it has evolved adding several features: Web content management, versioning, records management, workflow management, and so on.

Figure 4 shows the high-level architecture for the repository. The experiences request broker is an architectural element that can arrange the stored experiences and dispatch them according to three different perspectives (interfaces). In our architecture, the user views were decoupled from the experience management (insertion, updating).

Figure 5 shows the detailed architecture of the repository. It includes the internal interface, the experience's data entry built on top of the Alfresco ECM and the search interface. The internal interface was used by the interviewers and was deployed in Alfresco Share as a custom extension. This was structured according to three layers:

The persistence layer used the file system to store the experiences materials, while the database was needed for storing user information, user groups, content categorisation, and so on.

The search interface mainly intertwined tag-based, full Boolean, weighted and visual search strategies, to provide a rich experience search engine. The tagging experts used both the internal and the search interface. They downloaded the experiences to be tagged from the Alfresco repository, used QSR NVivo 9 (QSR International 2013), a third-party tagging software installed on their desktop environments, then exported the tags in Microsoft Excel format and uploaded xls files to the search interface through an ad-hoc view.

It was crucial to let the repository and the portal remain absolutely independent, to allow both the interfaces to evolve separately and to keep one of the subsystems online while the other was in maintenance/update mode. Developing an Alfresco extension, we defined the experiences data model as a common language adopted by the two interfaces. Moreover, we configured the interaction between the two interfaces by minimising their mutual relationship.

The Alfresco extension we developed included an experience export mechanism for transferring the data from the internal (the repository) to the external interface (the portal). The coordinator partner performed the export task from time to time, for example, when a massive data update was done. It allowed transferring of the resources’ links, and of the content metadata as well, for each completed experience.

The portal was designed and implemented by HOC-LAB of Polytechnic of Milan, according to the following requirements:

to support an innovative way of accessing rich information, emphasising exploration and serendipitous discovery over search,

The portal was implemented using standard Database Technology and an ‘experience engine’ with a novel interface. The portal was made public in December 2012. It currently hosts about 274 educational experiences, carried on in Italian schools, where the use of technology has been crucial.

In order to provide an effective exploration, a rich taxonomy of more than 30 facets and almost 200 facet values was developed. The taxonomy was revised several times since it was crucial to combine powerful exploration with understandability and usability. Thanks to an innovative HCI (Human Computer Interaction) approach (and novel supporting technology), the taxonomy is at the same time a tool for navigation and exploration as well as a tool for feedback. Once a value is selected within a facet, all the other values in all other facets ‘react’ to the choice. For example, if primary school is selected as school level, all the other facets (e.g. the technologies used) modify their values accordingly (so, for example, a scholar can see what technologies are used at primary school level).

Table 1 shows the list of the main facets. They range from factual elements (e.g. which tools are used) to interpretative ones (e.g. the impact generated by the adoption of a technology).

Table 2 shows an example of facet values for the facet ‘activities’. The user's at-a-glance understanding of a dataset is facilitated by numerous visualisation strategies. For example, all the elements of a set can be visualised as a ‘mosaic’ where shapes and colours are meaningful, as elements over a geographical map emphasising the geographical location of the experiences (see Figure 6) or as thumbnails (to support visually driven selection). Also, within the facets, different visualisations are possible, including absolute numbers, percentages and word clouds. Boolean logic, such as conjunction ‘and’, disjunction ‘or’, ‘exclusive or’, and negation ‘not’, support the use of the portal (see Figures 1 and 7).

A ‘shopping cart’ allowed the user to save the results of an exploration. Through proper commands, investigations could be saved, stored and shared, or ‘exported’ as PDF files.

If a specific experience was of interest, the user was provided first with an abstract and then with all the available materials, including documents, audio files and presentations.

Using a portal such as the one provided by L4ALL is a novelty for teachers. Therefore, focus groups were chosen (over surveys) as a way to investigate issues not fully known in advance. We wanted teachers to face the novelty together, share their first impressions and, through discussions and task performances, reach a shared opinion about the tool they were presented with. Three focus groups were held in autumn 2012, in cooperation with three different research groups: HOC-LAB (at Polytechnic of Milan Computer Science School); a team at the University of Perugia (Department of Education) and another at the University of Bologna (Department of Education). On the whole, 32 teachers were involved. They were all working as teachers across all school grades (from pre-school to high-school). The average age was 42. The three focus groups adopted a similar procedure:

First, the moderator gave a general introduction to the portal and the goal of the study: what it was about, what kinds of materials could be found and what kinds of scenarios could be supported (allotted time: 10 minutes).

The outcome of the focus groups was highly encouraging:

HCI features: after the initial difficulty of the apparent complexity of the interface, teachers became comfortable with it. Overall, they said that after a few minutes of usage, the interface became quite usable.

In order to evaluate the quality of the portal as a support for research activity, five research groups with different backgrounds (technology and pedagogy) were asked to use the portal for their research activities. Seven different investigations were carried out:

‘The Unexpected Learning: How Unexpected Benefits Can Be Generated Through ICT-Based Experiences’, by Polytechnic University of Marche

Some of the reports have already been turned into scientific papers (e.g. Di Blas and Paolini 2013).

The researchers were interviewed extensively and they outlined several advantages introduced by the portal:

Content: researchers showed appreciation of the in-depth understanding of the experiences afforded by the portal's wide range of materials.