“Photodentro” is the primary Digital Repository service of the Greek Ministry of Education for the digital learning resources of Primary and Secondary Education. It is an ecosystem of Open Educational Resource (OER) repositories and related services, which support the organization, documentation, efficient search, management and large-scale distribution of digital educational content to the educational community.

The “Photodentro” ecosystem includes the following web-based services:

A. The “Photodentro” Digital Educational Repositories

The Photodentro Repositories host Open Educational Resources (OERs) along with appropriate metadata to facilitate navigation, search, identification, and pedagogical utilization of learning resources. For the Ministry of Education, Religious Affairs and Sports, CTI has developed and operates seven (7) Photodentro digital repositories, each serving different purposes. Specifically:

Three (3) Digital Repositories with certified content from authorized users:

1. Photodentro Learning Object Repository (LOR): The National Repository of Digital Learning Objects, featuring dynamic simulations, visualizations, interactive maps, exercises, educational games, etc. URL: https://photodentro.edu.gr/lor   
2. Photodentro Educational Videos (Video): The National Repository of Educational Videos, hosting curriculum-related videos and short films. URL: http://photodentro.edu.gr/video
3. Photodentro Educational Software (EduSoft): The National Repository of Educational Software. URL: https://photodentro.edu.gr/edusoft

Four (4) Digital Repositories with content from the educational and scientific community:

1. Photodentro User-Generated Content (UGC): The National Repository of User-Generated Educational Material, where teachers can upload and share their digital learning objects. URL: https://photodentro.edu.gr/ugc
2. Photodentro Learning Scenarios (LS): The National Repository of Educational Scenarios. It provides the comprehensive online environment “Photodentro Learning Scenario Designer”, for creating, managing and sharing structured Educational Scenarios and Templates. URL: https://photodentro.edu.gr/ls
3. Photodentro Open Educational Practices (OEP): The National Repository of Open Educational Practices, where teachers share reusable teaching techniques, experiences, and reflections. URL: https://photodentro.edu.gr/oep
4. Photodentro Student Creations (i-create): The National Repository of Student Creations, operated by the Greek Educational TV. It hosts audiovisual works created by students for various competitions. URL: http://photodentro.edu.gr/i-create

All repositories are open to everyone—students, teachers, parents, and any interested parties. They host over 15,000 OERs covering a wide range of subjects and educational goals for Primary, Secondary, and General High School, available under CC licenses. For their documentation with metadata, the IEEE LOM-GR Photodentro Application Profile has been developed and used, following international standards. Photodentro Repositories are widely used by the educational and scientific community, with over 250,000 unique visitors per month.

B. The Greek National Aggregator of Educational Content and the “PHOTODENTRO” central portal

To provide a unified search for Open Educational Resources (OERs) for Primary and Secondary Education from a central point, and regardless of where they are stored, CTI has developed and operates the following services for the Greek Ministry of Education, Religious Affairs and Sports:

• The National Aggregator of Educational Content: A web-based service that collects metadata of digital resources from various repositories or other selected online sources, semantically unifies and enriches them to highlight their educational value, and makes them available through a central portal.
• The “PHOTODENTRO” central portal: Allows for the unified search of OERs for Primary and Secondary Education. URL: http://photodentro.edu.gr

The National Aggregator has collected and offers 19,000 OERs from 20 institutions and 16 different digital repositories. The central portal provides various search and navigation options for digital educational resources, based on their type, subject, thematic classification, educational level, student age, source repository, as well as free text search, or advanced search with multiple filters.

Additionally, CTI has developed and operates the following derivative services:

• Photodentro CULTURAL: A thematic aggregator of cultural educational resources, allowing unified search across thousands of selected digital resources from cultural collections of museums or other organizations. URL: http://photodentro.edu.gr/cultural
• Photodentro MICROCITES: Two autonomous microsites, focusing on Primary Education (Photodentro PRIMARY) and on English Language learning (Photodentro ENGLISH LANGUAGE). URL: https://micro.photodentro.edu.gr

Furthermore, CTI has developed and operates:

• The National Educational Content Aggregation Service: It is targeted at institutions such as ministries, educational establishments, museums, publishers, etc., having digital repositories, websites, or portals with open educational, cultural, or scientific resources and wishing to interconnect them with the Ministry’s digital repository services for broader utilization by teachers and pupils. The service includes processes for metadata harvesting, semantical unification, and enrichment, to facilitate their use in education. URL: https://aggregation-service.photodentro.edu.gr

Other related services developed and operated by CTI include:

• Photodentro Quality Seals: A repository and a comprehensive online service supporting the Quality Assurance (QA) process of OERs for Primary and Secondary Education, based on “Quality Seals” URL: http://photodentro.edu.gr/seals
• Online OBSERVATORY for the utilization of digital educational materials: A public, open Observatory, with statistics on the use and utilization of OERs of the Ministry’s digital repositories and related services. URL: https://observatory.dschool.edu.gr
• Photodentro SaaS: A service based on the “Software as a Service” model for providing digital educational repositories. URL: https://saas.photodentro.edu.gr