Phase 3: External Knowledge Expansion
Goal
Expand the knowledge base beyond the course boundary with precisely sourced external knowledge. The result should make the student's understanding deeper and broader than the course alone provides.
Step 0: Check operating mode
This phase operates in one of two modes, determined in Phase 0:
Mode A — Web-enabled (WebSearch + WebFetch available)
Run the full three-layer search strategy below.
Mode B — Curriculum-grounded (no web access)
Do NOT search the web. Instead, expand using stable, well-established knowledge from standard CS/engineering curricula. Every claim must be marked [Standard curriculum knowledge]. Do not invent URLs, paper titles, author names, or implementation details. If you are uncertain about a claim, omit it or flag it as [Uncertain — verify before exam]. The goal is to avoid hallucination causing review distortion, not to produce maximum volume.
If Mode B was chosen but the user now wants to enable web access, stop and ask them to grant WebSearch permission before continuing.
Expansion targets (both modes)
Process expansion targets in this priority order. Hard cap: maximum 15 targets per course. If there are more, present a ranked list and ask the user to confirm which to include.
- [EXPAND] markers from Phase 1 — concepts explicitly flagged as needing external investigation.
- Gaps and shallow topics from Phase 2 — concepts the course covers superficially or misses.
- Core concepts — central concepts that benefit from real-world grounding.
Mode A: Web-enabled search strategy
For each target, use up to three layers. Stop when you have sufficient quality material.
Layer 1: Industry & practical knowledge
Search for specific, deep content:
- Official documentation (Linux kernel docs, RFC, MDN, etc.)
- Engineering blogs from reputable companies (Google AI Blog, AWS Architecture, etc.)
- GitHub implementations (link to specific file/function, not repo root)
- Stack Overflow canonical answers for common confusions
Query tips: Use formal concept name + "implementation" / "in practice" / "architecture". Avoid generic "what is X" queries.
Layer 2: Academic literature
Search for:
- The original paper introducing the concept
- Recent surveys
- Papers that extend or challenge the course's treatment
For each paper: title, authors, arXiv ID or DOI, year, and 1-3 sentences on its relevance.
Layer 3: Cross-verification
When multiple sources are found, note where they agree (builds confidence) and where they disagree (flags nuance). If the course material contradicts an authoritative external source, flag this explicitly.
Mode B: Curriculum-grounded expansion
For each target concept:
- Describe the standard treatment of this concept in the field (textbook-level knowledge).
- Identify what the course's treatment adds, simplifies, or omits compared to the standard.
- Add the "bigger picture" context: where does this concept fit in the field? What problems does it address?
- Note common misconceptions that standard curricula address.
All content marked [Standard curriculum knowledge]. No fictional sources.
Organize by concept, not by search layer:
# Course Expansion: [Course Name]
## [Concept Name]
**Source in course:** [Lecture X, pp. Y-Z | Section X.Y] — [brief note on course treatment]
**Why expand:** [EXPAND marker / gap from synthesis / core concept]
### What the course doesn't cover
[The specific gap this expansion addresses.]
### Expanded understanding
[Mode A: what industry or research adds. Mode B: standard curriculum context.]
**Sources:**
- [Mode A] [Page Title](URL) — one-line note
- [Mode B] [Standard curriculum knowledge — topic area]
### Key insight
[2-4 sentences: what the student gains here that the slides don't provide.]
### Cross-verification note *(Mode A only)*
[Agreement/disagreement across sources, if applicable.]
---
Source citation rules
Mode A: Every factual claim needs a traceable source. Acceptable forms:
- Web:
[Title](full URL)
- Paper:
Author et al., "Title" (Year). arXiv:ID or DOI:xxx
- Docs:
[Doc Section](URL) with version
- Fallback:
[Standard curriculum knowledge — topic area] — use sparingly
Never cite a source you haven't actually retrieved. If search fails, write: "No high-quality external source found for [concept]; expansion based on course material and general domain knowledge."
Mode B: All claims [Standard curriculum knowledge]. No citations to sources not in hand.
Depth calibration
| Concept | Mode A depth | Mode B depth |
|---|
| Core + [EXPAND] marked | All 3 layers, 300-500 words | 200-300 words, curriculum context |
| Core, well-covered | Layer 1 only, 100-200 words | 100 words, brief context |
| Gap from Phase 2 | Layers 1-2, 200-300 words | 150 words, what standard treatment adds |
| Minor/tangential | Skip or 1-2 sentences | Skip |
Anti-patterns
- DO NOT dump raw search results without analysis.
- DO NOT expand more than 15 concepts — prioritize by value.
- DO NOT cite sources you haven't retrieved (Mode A) or invent sources (Mode B).
- DO NOT let this phase substitute for understanding the course — it enriches, it doesn't replace.
- DO NOT include outdated content without flagging it as historical.
- DO NOT (Mode B) state uncertain claims confidently. If unsure, omit or flag.