Exploring the Different Types of Open Educational Resources (OER)

Open Educational Resources (OER) have transformed how educators and learners access knowledge. UNESCO’s 2019 Recommendation on OER defines them as learning, teaching, and research materials in any format that reside in the public domain or are released under an open license, allowing free access, reuse, adaptation, and redistribution. But not all OER are alike. They come in different license types, media formats, quality levels, and authorship styles. Understanding these classifications helps educators choose the right resource for the right purpose – and use it legally and effectively.

Classification by license type 🔗

The license attached to an OER determines exactly what you can and cannot do with it. This is the most important classification to understand before you use, modify, or share any resource. There are three broad categories here: copyright protected, Creative Commons licensed, and public domain.

Copyright protected OER 🔗

Some educational materials are made freely available online but still carry traditional copyright. This means the creator retains exclusive rights over the work. You can typically view and use such resources for personal learning, but you cannot modify, redistribute, or repurpose them without explicit permission. These resources are technically “open” in terms of access (no cost to view), but they do not grant the full freedoms associated with true OER. A good example is Nature’s Scitable, which provides free science education content but does not use a Creative Commons license.

Creative Commons (CC) licensed OER 🔗

The vast majority of genuine OER carry a Creative Commons license. CC licenses allow creators to shift from the default “all rights reserved” to “some rights reserved,” granting users varying levels of permission. There are six standard CC licenses built from four conditions: Attribution (BY), ShareAlike (SA), NonCommercial (NC), and NoDerivatives (ND).

Here is a quick breakdown of the six licenses, from most to least permissive:

CC BY (Attribution) – The most open license. Others can distribute, remix, adapt, and build upon the work, even commercially, as long as they credit the original creator. Most OER advocates recommend this license for maximum reach.

CC BY-SA (Attribution-ShareAlike) – Same freedoms as CC BY, but any derivative work must be licensed under the same terms. This is the license used by Wikipedia and many open textbook projects.

CC BY-NC (Attribution-NonCommercial) – Others can remix and adapt the work for non-commercial purposes only, with attribution required.

CC BY-NC-SA (Attribution-NonCommercial-ShareAlike) – Combines non-commercial use with the requirement that derivatives carry the same license. This is considered the most restrictive license that still qualifies as OER.

CC BY-ND (Attribution-NoDerivatives) – Allows redistribution (even commercial) but no modifications. Since adapting content is a core OER principle, resources with this license are often not considered true OER.

CC BY-NC-ND (Attribution-NonCommercial-NoDerivatives) – The most restrictive CC license. It allows only verbatim copying for non-commercial use. Most open education experts argue that ND-licensed materials fall short of the full OER definition because they cannot be revised or remixed.

It is worth noting that Creative Commons licenses are available in three layers: a human-readable summary, a legally precise document, and machine-readable code that helps search engines discover openly licensed content.

Public domain OER 🔗

Public domain resources have no copyright restrictions at all. This happens either because the copyright has expired (as with many classic literary works), or because the creator has voluntarily waived all rights using a tool like CC0 (CC Zero). With public domain materials, you can do anything – copy, modify, distribute, and even use commercially – without needing to credit anyone (though attribution is still considered good practice). Project Gutenberg, which offers tens of thousands of free digitised books, is one of the best-known sources of public domain educational content.

Classification by media format 🔗

OER are not limited to text. They span a wide variety of media formats, making it possible to support different learning styles and teaching contexts. Here are the most common formats.

Text-based resources 🔗

Open textbooks remain the backbone of OER. Platforms like OpenStax (supported by Rice University) offer free, peer-reviewed textbooks covering subjects from biology and economics to psychology and history. The Open Textbook Library is another excellent repository where educators can find and review open textbooks. Beyond full textbooks, text-based OER also include lesson plans, course syllabi, lecture notes, assignments, and study guides.

Images and visual resources 🔗

Diagrams, infographics, photographs, and illustrations help learners grasp complex ideas more quickly. Platforms such as Pexels and Flickr’s Creative Commons section host large collections of openly licensed images that educators can freely use in presentations, handouts, and digital courses.

Video resources 🔗

Video is one of the most popular OER formats. Khan Academy built its global reputation on short instructional videos covering maths, science, economics, and more. MIT OpenCourseWare offers recorded lectures from across the entire MIT curriculum. Many openly licensed videos can also be found on platforms like Vimeo through their advanced CC license search filters.

Audio and podcasts 🔗

Audio-based OER include recorded lectures, language learning materials, and educational podcasts. These are particularly useful for learners who prefer auditory content or need to study on the go. Audiobook versions of public domain texts, for instance, are available through Project Gutenberg’s audio library.

Quizzes and assessments 🔗

Open test banks and quiz repositories allow educators to access ready-made assessment tools. Platforms like OER Commons host collections of quizzes, exams, and practice exercises that can be adapted and reused. These resources save significant time for teachers building course assessments from scratch.

Interactive simulations and games 🔗

Interactive OER combine education with engagement. PhET Interactive Simulations from the University of Colorado Boulder provides free maths and science simulations used by millions of students worldwide. Educational games, historical simulations, and virtual labs help develop problem-solving and critical thinking skills while reinforcing course content.

Classification by quality 🔗

Not all OER go through the same quality checks. The level of review a resource has received significantly affects its reliability and suitability for formal education. OER quality can be broadly grouped into three tiers.

Self-published OER 🔗

These are resources created and uploaded by individuals without any formal review process. A teacher might write a lesson plan and share it on a blog or a repository. While many self-published OER are useful and well-crafted, there is no external mechanism to verify their accuracy, completeness, or pedagogical soundness. Educators using self-published OER should evaluate the content carefully before adopting it for a course.

Peer-reviewed OER 🔗

Peer-reviewed OER have been evaluated by other experts or educators before being published or listed on a platform. For example, OpenStax textbooks go through a rigorous review process involving subject-matter experts. The MERLOT repository is well known for hosting curated, peer-evaluated educational resources contributed by an international community. Peer review adds a significant layer of credibility, making these resources more suitable for formal academic use.

Refereed OER 🔗

Refereed OER undergo the most rigorous quality control – similar to academic journal articles. An editorial board or panel of reviewers assesses the resource for accuracy, pedagogical quality, and alignment with learning objectives before it is approved for publication. These resources carry the highest level of trust and are often found in institutional repositories or published by university presses. The University of Pittsburgh’s OER guide notes that one key advantage of OER is that they can be continuously updated and improved through community feedback, which traditional textbooks cannot easily achieve.

Quality assurance remains a key challenge for the OER movement. A meta-analysis reported by the University of Hong Kong library found that simply changing a resource’s license from proprietary to open does not automatically improve learning outcomes – factors like content accuracy, clear learning objectives, and effective instructional design all play a role.

Classification by authorship style 🔗

Who creates an OER, and how they create it, also matters. Authorship style affects the diversity of perspectives, the pace of updates, and the overall richness of the resource.

Individually developed OER 🔗

These resources are created by a single author – typically a teacher, professor, or subject expert. An individually authored open textbook, for example, reflects one person’s expertise and pedagogical approach. The advantage is consistency in voice and structure. The drawback is that it can be limited in perspective and slower to update. Many OER courses available on platforms like Saylor Academy were originally developed by individual educators who chose to share their work openly.

Collaboratively created OER 🔗

Collaborative OER are produced by teams of contributors – sometimes from different institutions or even different countries. Wikipedia is the most prominent example of a collaboratively created resource, with millions of articles maintained by volunteer editors around the world. In the education space, eCampusOntario’s Open Library contains textbooks developed collaboratively by faculty across Ontario’s post-secondary institutions. Carnegie Mellon University’s Open Learning Initiative (OLI) takes collaboration even further – its courses are built by multidisciplinary teams of learning scientists, content experts, and software engineers working together.

Collaboratively developed OER tend to benefit from diverse viewpoints, faster error correction, and broader applicability. However, they may sometimes lack a unified voice or consistent tone. The most effective collaborative OER projects use structured editorial workflows and clearly defined contributor roles to maintain coherence.

Examples of popular OER platforms by category 🔗

Understanding the types of OER is more practical when you know where to find them. Here is a summary of key platforms organised by the type of OER they primarily support.

For open textbooks: OpenStax offers free, peer-reviewed textbooks for higher education. The Open Textbook Library provides faculty-reviewed books that can be downloaded free or printed affordably. LibreTexts hosts interactive, openly licensed textbooks across multiple disciplines.

For complete courses: MIT OpenCourseWare covers virtually every MIT department with free course materials. Khan Academy provides instructional videos and exercises from school-level through to introductory college content. Coursera partners with universities globally to deliver full courses (though not all are openly licensed).

For multimedia and supplementary materials: OER Commons is one of the largest collections of diverse OER, including courses, textbooks, and ancillary resources. PhET Simulations provides free interactive science and maths tools. The Internet Archive’s OER Library contains video lectures, supplemental materials, and full courses.

For searching across repositories: The OASIS search engine lets users find OER by subject or material type across multiple repositories. The Mason OER Metafinder (MOM) from George Mason University searches across 15 major OER repositories simultaneously.

No matter what type of resource you need – a single diagram, a complete course, or an interactive simulation – there is likely an OER available that fits. The key is to check the license, evaluate the quality, and adapt it thoughtfully for your teaching context.

Why understanding OER types matters for educators 🔗

Classifying OER is not just an academic exercise. It has real implications for how educators plan their teaching. Choosing the right license type ensures you stay legally compliant when adapting materials. Selecting the appropriate media format helps you match resources to your students’ learning preferences. Evaluating quality protects your students from inaccurate or poorly structured content. And knowing whether a resource was individually or collaboratively authored helps you assess its depth and perspective.

The UNESCO OER Recommendation encourages member states to build capacity for creating, accessing, reusing, and redistributing OER. As more governments and institutions invest in open education, the range and quality of available OER will continue to grow. For educators, staying informed about these types and classifications is the first step toward making the most of what the open education movement has to offer.

What do you think? Which type of OER – based on license, format, quality, or authorship – do you find most useful in your teaching practice? And how do you currently evaluate the quality of an OER before using it in your classroom?

References

1. https://www.unesco.org/en/open-educational-resources/mandate
2. https://www.nature.com/scitable/
3. https://creativecommons.org/share-your-work/cclicenses/
4. https://iastate.pressbooks.pub/oerstarterkit/chapter/creative-commons/
5. https://wiki.creativecommons.org/wiki/Creative_Commons_and_Open_Educational_Resources
6. https://www.gutenberg.org/
7. https://openstax.org/
8. https://open.umn.edu/opentextbooks/
9. https://www.pexels.com
10. https://www.flickr.com/creativecommons/
11. https://www.khanacademy.org/
12. https://ocw.mit.edu/
13. https://www.oercommons.org/
14. https://phet.colorado.edu/
15. https://www.merlot.org/
16. https://pitt.libguides.com/openeducation
17. https://libguides.lib.hku.hk/openscience/OER
18. https://www.saylor.org/
19. https://ecampusontario.pressbooks.pub/facultyoertoolkit2/chapter/types-of-oer/
20. https://libretexts.org/
21. https://about.coursera.org/
22. https://archive.org/details/education
23. https://oasis.geneseo.edu/
24. https://www.unesco.org/en/open-educational-resources