Languages
Language courses
Free Spanish for beginners is available now: 482 connected paragraph-pages across nine themes, with explanations in five languages.
Browse languagesEDDA EDU · Free online courses
Understand the idea.
Test the structure.
Each course separates explanation from diagnosis. When an answer is wrong, the learner sees the reason, returns to the precise explanation, and then attempts the same problem again.
Mathematics · Public beta
Middle School Mathematics
Free US Grades 6–8 mathematics: 24 units, 96 theory pages, and 24 synthesis diagnostics organized around Common Core domains.
Open MathematicsOne learning architecture
Explanation, diagnosis, targeted return
- Build the concept
Theory is presented in a deliberate sequence.
- Test the whole structure
A synthesis task checks several linked ideas.
- Repair the exact gap
Every diagnostic error points to a specific explanation.
- Return and answer again
The learner comes back to the same task with the route preserved.