# Teacher
Teacher is a Codex plugin for two related jobs: helping someone understand a subject now, and designing learning material that can be delivered later.
It keeps those jobs separate so a direct question stays a direct answer, while a course-design request gets explicit performance goals, credible assessment evidence, practice, feedback, accessibility, and maintenance.
## What it includes
| Skill | Use it for |
| --- | --- |
| `teacher:teach` | Source-grounded explanations, code or system walkthroughs, and guided learning sessions. It deliberately stays out of pure summarization, extraction, and rewriting. |
| `teacher:design-course` | Reusable lessons, workshops, courses, onboarding paths, curricula, assessments, and audits. It checks whether instruction is actually the right intervention before designing it. |
The package also includes shared guidance for source truth and learning science, reusable course-design templates, and nine adversarial evaluation cases.
## Install
Register TheGreenCedar's public marketplace, then install Teacher:
```sh
codex plugin marketplace add TheGreenCedar/AgentPluginMarketplace --ref main
codex plugin add teacher@TheGreenCedar
```
You can also register the marketplace from the terminal and install `teacher` from the Plugins directory in the Codex app. Start a new task after installation so the plugin is available from the beginning.
## Use
Ask for immediate teaching when you need to understand or reason about something:
```text
@Teacher Teach me this payment retry subsystem so I can debug it safely.
I know Rust and distributed-systems basics. Trace one request from input to outcome.
```
Ask for course design when the output will be reused with other learners:
```text
@Teacher Design a 90-minute onboarding workshop that prepares new engineers
to diagnose this payment retry subsystem. Include a realistic assessment and pilot plan.
```
A useful request names the topic, what the learner should be able to do, their starting point, and the desired format or depth.
## Trust and privacy
Teacher ships instructions, references, templates, and evaluation prompts. It has no MCP server, hosted backend, telemetry, credentials, or background process. When a request depends on changing or private material, the plugin tells Codex to inspect the sources available in that task and distinguish observed facts from inference and unknowns.
## Validate
With the bundled Codex creator skills installed:
```sh
python3 ~/.codex/skills/.system/skill-creator/scripts/quick_validate.py skills/teach
python3 ~/.codex/skills/.system/skill-creator/scripts/quick_validate.py skills/design-course
python3 ~/.codex/skills/.system/plugin-creator/scripts/validate_plugin.py .
```
The behavioral cases and rubric live in [`evals/`](evals/).
## License
Original Teacher material is available under the [Apache License 2.0](LICENSE). Copyright 2026 Albert Najjar.
Portions of the teaching and course-design material are adapted from MIT- and CC BY 4.0-licensed sources. The affected files, credits, licenses, and changes are recorded in [Third-party notices](THIRD_PARTY_NOTICES.md).