Why This Matters

You open the unit planner template, scroll to the "Key Concept" field, and freeze. There's a dropdown list of maybe fifteen words — Change, Systems, Connections, Perspective — and none of them feels obviously right for the unit you're about to teach. So you pick one that sounds vaguely appropriate, move on, and never think about it again until your coordinator asks you to justify it in a planning meeting. You genuinely don't remember why you chose it. That's not a personal failing — it's what happens when concept selection is treated as a dropdown formality instead of a decision.

Understand the Idea

In the MYP, concepts operate at two levels, and mixing them up is the root of most "arbitrary-feeling" unit designs.

Key concepts are broad, transdisciplinary organizers — big ideas like Change, Systems, or Perspective that show up across every subject group, from Science to Language and Literature to Physical and Health Education. Transdisciplinary means the concept isn't owned by one subject; it can organize a unit in Math just as easily as a unit in History. A key concept gives a unit its widest lens.

Related concepts are subject-specific and narrower. They add depth within a discipline — a term like "causality" makes more immediate sense in Individuals & Societies (the MYP subject group covering history, geography, economics, and civics) than it might in Visual Arts, where a related concept like "expression" or "representation" might fit better. Related concepts are where the key concept gets sharpened into something your specific subject content can actually use.

📌 Official source: The exact list of key concepts, and the related concepts recommended per subject group, are published by the IB and are periodically refined. Don't treat any list you see in this handbook — or anywhere online — as permanently fixed. Confirm the current wording in your subject guide or MYP: From Principles into Practice before you finalize a unit.

Think of the pairing like a camera. The key concept sets the zoom level — wide enough to matter across the whole curriculum. The related concept focuses that same wide idea onto the specific texture of your subject's content. "Change" alone could mean almost anything. "Change" paired with "transformation" in a Science unit points toward chemical or physical transformation specifically; "Change" paired with "causality" in an Individuals & Societies unit points toward why things change, not just that they do.

This pairing exists to prevent two opposite failures. Pick a key concept with no related concept, and your unit stays too abstract to grip any real content — a common symptom is a unit that could, honestly, be about anything. Pick several related concepts with no clear anchor, and you get what experienced planners call conceptual clutter: three or four ideas competing for attention, none of which students can actually name by the end of the unit. The goal is one clear key concept, and typically one or two related concepts — enough to add precision, not so many that the through-line disappears.

See It in Practice

Imagine two teachers, both planning units broadly about environmental change, in two different subjects.

Individuals & Societies, Grade 8, unit on deforestation and land use: The teacher's first instinct is to pick "Change" and stop there — technically defensible, but so broad it could describe half the units in the school. She adds a related concept: "causality." Now the unit has a real question underneath it: not just "what changed in this region," but "what caused it to change, and could the outcome have been different." Every lesson can now be interrogated against that pairing — a lesson on satellite land-use data either builds toward "causality" or it's a detour.

Sciences, Grade 8, unit on ecosystem disruption after a chemical spill: Same rough topic area — environmental change — but a different related concept fits the content better: "transformation," which points students toward the physical and chemical mechanisms of change rather than the human decision-making behind it. "Change" plus "transformation" here produces a unit about how an ecosystem's chemistry shifts, not why people made the choices that caused the spill — a legitimately different unit from the one above, even though both start from "environmental change."

Weak version: A teacher picks "Change" and "Perspective" together for the deforestation unit, reasoning that both "sound relevant." Neither is rejected explicitly, so the unit drifts between "what changed" and "whose viewpoint matters," never fully answering either. Ask a student at the end what the unit was really about, and you'll get two different answers depending on who you ask.

Strong version: The teacher chooses "Change" + "causality," and explicitly rejects "Perspective" in her planning notes: "Perspective would pull the unit toward comparing stakeholder viewpoints, which is valuable but is not our focus this unit — we're building the skill of tracing cause and effect in land-use decisions. Perspective may anchor a future unit instead." That one sentence of rejection is what makes the choice defensible rather than arbitrary.

🧠 Teacher insight: Naming the alternative you didn't choose, and why, is often more clarifying than the choice itself. It forces you to notice what your unit is not trying to do.

Apply It

Open the unit you're currently planning or about to teach.

🧭 Planning decision: Write down a candidate key concept and one, or at most two, related concepts. Then write one full sentence explaining why a plausible second-best key concept would have been the weaker choice for this specific content. For example: "I considered 'Systems' instead of 'Change,' but this unit is really about tracking a single trajectory over time rather than the interaction of multiple parts, so 'Change' fits the content more precisely."

This sentence — the justification against a named alternative — is the concrete artefact you're producing today. Put it directly into your unit planner's key concept field, even if the template doesn't ask for it explicitly; it will save you in the planning meeting where someone asks "why this concept?"

📎 Download: The Concept Selection Worksheet includes a justification field structured exactly like the sentence above, plus a short list of illustrative key-concept and related-concept examples per subject group to prompt your thinking — reminder: confirm the current official list before finalizing.

Avoid This

Symptom: you can state your key concept, but you freeze if asked "why not the other one." This means the choice was instinct, not reasoning. Fix: always write the one-sentence rejection of a specific alternative, not just the chosen concept.

Symptom: your unit lists three or four related concepts. This is conceptual clutter — a sign the unit hasn't decided what it's actually about. Fix: cut to one or two and ask which content would have to be removed to make the others true.

Symptom: the same key concept appears in every unit you plan this year. This suggests a default reflex rather than a real match to content. Fix: before finalizing, deliberately consider at least one alternative key concept for every unit, even if you end up keeping your first choice.

⚠️ Common trap: Choosing a related concept because it's the one you personally find interesting, rather than the one your specific content actually demands. Interesting to you and demanded by the content are not always the same thing.

Check Yourself

Quick check — yes or no:

  1. Can you name the specific alternative key concept you considered and rejected, and why?
  2. Do you have one or two related concepts, not three or more?
  3. Could a student, asked mid-unit, explain in one sentence what your related concept adds beyond the key concept?

Continue Learning

→ Next step: Article 8 — Global Contexts: Giving the Unit a Reason to Exist, where your concept pairing gets connected to a real-world lens. Download: Concept Selection Worksheet. 📌 Official source: check your current subject guide or MYP: From Principles into Practice for the authoritative current list of key concepts and subject-group related concepts.