Chengyu teach by material

因材施教 — teach by the material

因材施教 (yīn cái shī jiào) — "according to the material, apply teaching". Match the medium AND the depth of an output to the actual consumer and use-mode. The same content delivered in the wrong format degrades just as much as the same content delivered at the wrong depth.

Operator extension: format is a calibration dimension

Default agent behaviour is "always emit text into the chat". The operator's refinement: format itself is one of the variables, not just verbosity. Different consumers parse different formats; defaulting to text is one failure mode among many.

Format	Best for	Cost
Inline chat text	quick answer, single-shot question, operator-in-flow	low
Markdown file	doc that gets grep'd, README, internal note	low-mid
HTML rich-render dashboard (~/rich-renders/)	multi-item synthesis, side-by-side comparison, decision-with-options	mid
PPTX	talk, walkthrough, pitch, time-bounded presentation to audience	mid-high
DOCX	formal deliverable, contract, signed document, exportable artifact	high
Video	outside native scope — requires autovideo pipeline; too heavy to be default	very high

When this applies

Symptoms that this schema applies:

• Operator asks for "explanation" — calibrate: how technical are they? how much time do they have? prose or slides? skim or reference?
• Multiple items to compare (≥5) — HTML dashboard (table, side-by-side) almost always beats text list. The stop-hook in this homelab specifically calls this out as a default.
• Walkthrough of a decision with options — slides beat prose for the same content because slides force you to one-idea-per-frame.
• Formal deliverable — DOCX beats markdown for headers, page numbers, signatures, export to external parties.
• Internal note that needs to be searchable — markdown beats DOCX; markdown beats inline chat text.
• Quick answer — inline text beats anything else. Don't over-format.
• Cross-session reference — file (markdown or HTML) beats chat (chat scrolls away).

Behavior

1. Identify the consumer. Who reads this? Operator only? Operator's team? External? Machine consumer?
2. Identify the use mode. Skim once? Referenced repeatedly? Presented to live audience? Legal/formal artifact? Compounded with prior work?
3. Pick the format that matches consumer × use-mode. Use the rough matrix above; deviate when context demands.
4. Calibrate verbosity within the chosen format. Format selection is the outer loop; depth-calibration is the inner loop.
5. If unsure between two formats, ASK the operator — format choice has real cost (PPTX takes minutes; inline chat text takes seconds). Don't burn the cost speculatively.

Cross-reference

This skill pairs with the stop-hook heuristic: "If this turn produced a multi-item synthesis (≥5 items, e.g. triage/audit/survey/comparison), emit rich HTML dashboard." That heuristic is chengyu-teach-by-material applied to a specific consumer-use-mode (operator scanning multi-item synthesis).

Anti-pattern

Defaulting to text for everything. Text-by-default is a calibration failure. Multi-item comparisons especially benefit from HTML structure; presentations especially benefit from PPTX; formal docs benefit from DOCX. The chengyu's whole point is the format is a variable.

Over-formalising. Using DOCX when markdown would do, or PPTX when a paragraph would suffice. Formality fatigue is real — operator stops reading the polished deliverable for what would have been a 3-sentence answer.

Over-prettifying. Building HTML dashboards for single-paragraph answers. The dashboard has cost (to author, to render, to navigate); use it when the structural value justifies the cost.

Pretending video is in scope. The autovideo pipeline exists but is heavy enough that it's not a native capability. Don't promise a video render without explicitly checking with operator whether the pipeline run is justified.

Confusing format-calibration with depth-calibration. They're orthogonal axes. A PPTX can be terse; a chat reply can be deep. Pick the format and pick the depth independently.

Etymology

From the Analects (論語) — Confucius is recorded as giving different answers to the same question depending on who asked. The canonical example:

子路問：「聞斯行諸？」 — Zilu asked: "When I hear something, should I act on it?" 子曰：「有父兄在，如之何其聞斯行之！」 — Confucius said: "Your father and elder brother are still alive — how can you just act on what you hear?"

冉有問：「聞斯行諸？」 — Ranyou asked the same question. 子曰：「聞斯行之。」 — Confucius said: "When you hear it, act on it."

公西華曰：「赤也惑，敢問。」 — Gongxihua asked: "Same question, opposite answers — please explain." 子曰：「求也退，故進之；由也兼人，故退之。」 — Confucius said: "Ranyou is timid, so I push him forward; Zilu is bold for two, so I rein him in."

The teaching matches the student. Same question, different answer. Same content, different delivery.

Agentic translation extends past depth-calibration (verbosity, technical level) into format-calibration (medium itself): not just HOW MUCH you say, but in WHAT FORM. The operator's refinement is sharp: the format is part of the material being taught, and choosing the wrong format is choosing the wrong material.