Top 10 Free Open Educational Resources for STEM Teachers in 2026

Published: June 2026 | Reading Time: ~6 minutes

Table of Contents

1. What Are Open Educational Resources?
2. Why STEM Teachers Need OERs in 2026
3. Top 10 Free OERs for STEM Teachers
   • 1. Khan Academy
   • 2. PhET Interactive Simulations
   • 3. CK-12 Foundation
   • 4. NASA Education
   • 5. MIT OpenCourseWare
   • 6. Desmos
   • 7. NRICH Maths
   • 8. Code.org
   • 9. OpenStax
   • 10. Smithsonian Learning Lab
4. FAQs

What Are Open Educational Resources?

Open Educational Resources (OERs) are teaching and learning materials that are freely available for anyone to use, adapt, and redistribute. They include textbooks, lesson plans, videos, simulations, assessments, and full courses — all at no cost.

Unlike paywalled platforms, OERs are built on the belief that quality education should be accessible to every student and teacher, regardless of budget or geography. In a world where school budgets are constantly squeezed, OERs are one of the most powerful tools in a teacher's arsenal.

Why STEM Teachers Need OERs in 2026

STEM education has never been more important — or more expensive to resource properly. Lab equipment, licensed software, and updated textbooks drain school budgets fast. Meanwhile, the skills gap in science, technology, engineering, and mathematics continues to grow globally.

OERs solve a real problem: they give STEM teachers access to high-quality, curriculum-aligned, regularly updated content without spending a cent. In 2026, many of these platforms have also integrated AI-powered personalization, making them even more effective than many paid alternatives.

Whether you teach kindergarten coding or AP Physics, there's a free resource built exactly for you.

Top 10 Free OERs for STEM Teachers

1. Khan Academy

Best for: Math, Science, Computing | Grades: K–12 and beyond

Khan Academy remains one of the most comprehensive free learning platforms on the planet. Teachers get access to thousands of instructional videos, practice exercises, and full unit plans across every STEM subject — from basic arithmetic to AP Calculus, biology, chemistry, and computer science.

In 2026, Khanmigo — its AI tutor — now assists teachers with lesson planning, student feedback, and differentiated instruction, all at no cost for educators.

Standout feature: Detailed student progress dashboards that let teachers identify exactly where each learner is struggling.

2. PhET Interactive Simulations

Best for: Physics, Chemistry, Biology, Earth Science | Grades: 5–12

Developed by the University of Colorado Boulder, PhET offers over 150 free, research-based interactive simulations. Students can build virtual circuits, explore molecular structures, experiment with gravity, and observe chemical reactions — all in a safe, browser-based environment.

These simulations are especially valuable for schools without well-equipped labs. Every simulation is grounded in peer-reviewed educational research and designed to build genuine conceptual understanding.

Standout feature: Available in 90+ languages, making it one of the most globally accessible STEM tools available.

3. CK-12 Foundation

Best for: All STEM subjects | Grades: K–12

CK-12 is a flexible, customizable platform offering free digital textbooks ("FlexBooks"), practice problems, videos, and simulations. What makes it stand out is the ability for teachers to modify existing content or create their own custom textbooks tailored to their curriculum.

The platform's AI tutor provides students with step-by-step guidance, and teachers can assign content, track progress, and generate assessments — all for free.

Standout feature: Fully customizable textbooks that align to your specific state or national standards.

4. NASA Education

Best for: Earth Science, Physics, Space Science, Engineering | Grades: K–12 and Higher Ed

NASA's education portal is a goldmine for STEM teachers. It offers lesson plans, student activities, multimedia resources, and real mission data — all developed by actual NASA scientists and educators. There's no better way to make space science feel real than using data from active missions.

Resources are organized by grade level and subject, and many tie directly to current NASA missions, keeping content fresh and relevant.

Standout feature: Access to real NASA mission data that students can analyze like working scientists.

5. MIT OpenCourseWare

Best for: Advanced Math, Engineering, Computer Science, Physics | Grades: High School Advanced / Higher Ed

MIT OpenCourseWare (OCW) publishes materials from over 2,500 MIT courses — completely free. For high school teachers delivering advanced or AP-level STEM content, OCW is an exceptional source of rigorous problem sets, lecture notes, and assessments used by one of the world's top universities.

It's also perfect for teachers who want to deepen their own subject knowledge.

Standout feature: Full course materials from MIT — problem sets, exams, and lecture notes — available to anyone.

6. Desmos

Best for: Mathematics | Grades: 6–12

Desmos is a free, beautifully designed graphing calculator and math activity platform. Teachers can assign interactive activities where students explore functions, geometric transformations, statistics, and more — all visually and dynamically.

The Desmos Teacher Activity Builder lets educators create custom math explorations, and the platform's existing activity library is extensive and classroom-tested.

Standout feature: Real-time class view — teachers can see every student's graph and work as it happens, live on screen.

7. NRICH Maths

Best for: Mathematics | Grades: K–12

NRICH, developed by the University of Cambridge, offers thousands of free rich math tasks, puzzles, articles, and games designed to build deep mathematical thinking — not just procedural skills. It's particularly strong for developing problem-solving, reasoning, and mathematical communication.

Every resource is curriculum-mapped and comes with teacher notes, making lesson planning straightforward.

Standout feature: Emphasis on mathematical reasoning and open-ended problem-solving — perfect for developing higher-order thinking.

8. Code.org

Best for: Computer Science, Coding, Computational Thinking | Grades: K–12

Code.org is the gold standard for free computer science education. It offers complete, standards-aligned CS curricula for every grade level — from block-based coding for kindergarteners to full AP Computer Science Principles courses for high schoolers.

Courses are engaging, self-paced, and require no prior coding experience from the teacher. Professional development is also free, making it ideal for teachers new to CS instruction.

Standout feature: Full K–12 CS curriculum with free teacher professional development included.

9. OpenStax

Best for: Biology, Chemistry, Physics, Statistics, Calculus | Grades: High School and College

OpenStax, from Rice University, provides peer-reviewed, openly licensed textbooks for the most commonly taught STEM courses. These aren't watered-down free texts — they are rigorous, college-level resources used by millions of students worldwide.

Each textbook is available online, as a PDF, and in print (at low cost). Supplementary materials including test banks, lecture slides, and instructor resources are available free to verified educators.

Standout feature: Full college-level STEM textbooks, peer-reviewed and free — no strings attached.

10. Smithsonian Learning Lab

Best for: Science, Engineering, Environmental Education | Grades: K–12

The Smithsonian Learning Lab gives teachers access to millions of digital resources from the Smithsonian's vast collections — images, artifacts, primary sources, videos, and interactive activities. Teachers can build custom digital collections around any STEM topic and assign them directly to students.

It's especially powerful for connecting science and engineering content to real-world history, culture, and current events.

Standout feature: Millions of authentic Smithsonian resources that bring real-world context to STEM learning.

FAQs

Q1: Are these resources truly free, or do they have hidden costs? All ten platforms listed here offer their core content completely free. Some — like CK-12 and Khan Academy — offer optional premium or school-wide features at cost, but everything a classroom teacher needs is accessible without paying anything.

Q2: Do I need to be tech-savvy to use these platforms? Not at all. Most platforms — especially Khan Academy, Code.org, and CK-12 — are designed with busy, non-technical teachers in mind. Setup is minimal, and most platforms offer tutorials and teacher guides to get you started quickly.

Q3: Can these resources replace textbooks entirely? For many subjects, yes. OpenStax and CK-12 in particular are built to serve as full textbook replacements. Others like PhET and Desmos are best used as supplements alongside core instruction. The combination of two or three platforms often covers all your needs.

Q4: Are these platforms aligned to curriculum standards like Common Core or Next Generation Science Standards (NGSS)? Most of them are. Khan Academy, CK-12, Code.org, and PhET all explicitly align content to Common Core Math, NGSS, and CSTA standards. Always check a platform's standards alignment page for your specific region.

Q5: Can students access these resources at home for independent study? Yes — all ten platforms are internet-accessible, and several (CK-12, OpenStax, PhET) offer offline options or downloadable content. This makes them ideal for homework, revision, and self-paced learning beyond the classroom.

Q6: Which platform is best for a teacher just starting with OERs? Start with Khan Academy — it covers the broadest range of subjects, has the most intuitive teacher dashboard, and includes built-in AI support. Once you're comfortable, layer in PhET for science experiments and Desmos for math explorations.

The best teaching tools aren't always the most expensive ones. These ten platforms put world-class STEM education within reach of every teacher and every student — regardless of school budget. Start with one, explore it deeply, and build from there.