# Directory Structure for Phases and Lessons in AI Engineering from Scratch: A Complete Guide > Explore the AI Engineering from Scratch directory structure. Learn the `phases/-/-/` pattern with code, docs, and outputs folders for organized learning. - Repository: [Rohit Ghumare/ai-engineering-from-scratch](https://github.com/rohitg00/ai-engineering-from-scratch) - Tags: how-to-guide - Published: 2026-08-31 --- **The curriculum organizes content under a top-level `phases/` directory using a hierarchical pattern of `phases/-/-/`, where every lesson contains three standardized sub-folders: `code/`, `docs/`, and `outputs/`.** The open-source educational repository **AI Engineering from Scratch** by `rohitg00` implements a deterministic directory structure for phases and lessons that separates learning materials into modular, reproducible units. This architecture, defined in the repository root [`README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/README.md) and enforced across all phase READMEs, allows learners to locate runnable implementations, narrative explanations, and generated artifacts through predictable file paths. ## Top-Level Phase Organization The repository root contains a single `phases/` folder that houses the entire curriculum. Each phase follows a strict naming convention: ``` phases/-/ ``` Here, `` represents a two-digit zero-padded index (e.g., `00`, `01`, `02`) and `` describes the thematic focus in kebab-case. According to the source code, valid phase directories include: - `phases/00-setup-and-tooling/` – Environment configuration and tooling - `phases/01-math-foundations/` – Mathematical prerequisites These paths are documented in the phase-level README files located at [`phases/00-setup-and-tooling/README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/phases/00-setup-and-tooling/README.md) and [`phases/01-math-foundations/README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/phases/01-math-foundations/README.md), which enumerate their respective lessons and hyperlink to each lesson folder. ## Lesson Directory Naming Convention Inside each phase directory, individual lessons reside in sequentially numbered folders that mirror the phase naming pattern: ``` phases/-/-/ ``` The `` placeholder indicates a two-digit lesson index (e.g., `01`, `02`), while `` provides a descriptive, human-readable name. Concrete examples from the repository include: - `phases/00-setup-and-tooling/01-dev-environment/` – The first lesson of Phase 0 - `phases/01-math-foundations/01-linear-algebra-intuition/` – The first lesson of Phase 1 As specified in the root [`README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/README.md) under "The shape of a lesson" section, this convention ensures lessons sort chronologically by filesystem default while maintaining descriptive identifiers. ## The Three-Pillar Lesson Structure Every lesson folder enforces a consistent three-part layout that separates concerns across implementation, documentation, and artifacts: - **`code/`** – Located at `phases/...//code/`, this folder contains runnable implementations in Python, TypeScript, Rust, or Julia. - **`docs/`** – Found at `phases/...//docs/`, typically containing [`en.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/en.md) with the lesson narrative and theoretical explanations. - **`outputs/`** – Stored at `phases/...//outputs/`, this directory holds generated artifacts such as AI prompts, reusable skills, autonomous agents, or MCP (Model Context Protocol) servers. The root [`README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/README.md) explicitly canonizes this structure as the standard lesson shape, ensuring contributors maintain consistency across the curriculum. For example, navigating to `phases/01-math-foundations/01-linear-algebra-intuition/` reveals these three sub-directories, with implementations in `code/`, explanatory text in [`docs/en.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/docs/en.md), and resulting AI artifacts in `outputs/`. ## Practical Navigation Commands To explore the directory structure for phases and lessons from the command line, use standard Unix utilities to inspect the hierarchy: ```bash # List all phases in chronological order ls phases/ # View lessons within a specific phase ls phases/01-math-foundations/ # Display complete lesson tree including code, docs, and outputs tree phases/01-math-foundations/01-linear-algebra-intuition/ ``` These commands reveal the numeric sorting that the two-digit index enables, allowing `00` to appear before `01` and preserving lesson sequence across filesystem listings regardless of alphabetical slug names. ## Summary - The **directory structure for phases and lessons in AI Engineering from Scratch** roots at `phases/` with two-digit indexed phase folders following the pattern `-/`. - Each phase contains lesson directories named `-/`, creating predictable paths like `phases/01-math-foundations/01-linear-algebra-intuition/`. - Every lesson enforces a three-folder standard: **`code/`** for implementations, **`docs/`** for narrative content (specifically [`en.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/en.md)), and **`outputs/`** for AI artifacts such as prompts and agents. - This architecture is documented in the root [`README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/README.md) "shape of a lesson" section and implemented consistently across phase READMEs such as [`phases/00-setup-and-tooling/README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/phases/00-setup-and-tooling/README.md). ## Frequently Asked Questions ### What is the exact path pattern for lesson directories? Lessons follow the nested pattern `phases/-/-/`, where both `` and `` are two-digit zero-padded numbers. For instance, the first lesson of the setup phase resides at `phases/00-setup-and-tooling/01-dev-environment/` according to the repository's source code. ### What file contains the narrative explanation for each lesson? Each lesson stores its primary documentation in [`docs/en.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/docs/en.md) relative to the lesson root. This file contains the narrative explanation and theoretical background corresponding to the runnable code in the sibling `code/` directory. ### What types of files belong in the outputs folder? The `outputs/` directory contains generated artifacts such as AI prompts, reusable skills, autonomous agents, or MCP servers produced during the lesson. This separation distinguishes transient build artifacts from immutable source code and documentation. ### Where is the directory structure formally defined? The canonical structure is defined in the root [`README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/README.md) of the `rohitg00/ai-engineering-from-scratch` repository under the section titled "The shape of a lesson". Additionally, each phase directory contains a [`README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/README.md) file (e.g., [`phases/01-math-foundations/README.md`](https://github.com/rohitg00/ai-engineering-from-scratch/blob/main/phases/01-math-foundations/README.md)) that validates the lesson index and naming conventions for that specific phase.