How do you live well on a changing Earth?
Every unit comes back to it. The short version of the answer this course is building toward: living well on a changing Earth requires deciding what to trust, what to protect, and what to give up. Those three decisions are what the units below take turns on.
Why this page exists
Most of what you do in this course is designed to transfer. You build a habitability framework in Unit 1 from planets you have been taught, then use it on a planet nobody has taught you. You learn OPVL in Unit 0 on news articles and use the same four letters in Unit 4 on climate projections. Every unit ends with you defending something in front of an audience that is not your teacher.
None of that was written down anywhere. This page writes it down. It is not new content and it does not change any assignment. It names the shape that was already there, so you can see what a unit is actually for while you are in the middle of it.
The four threads
A thread is something that does not belong to one unit. It starts somewhere, gets harder, and keeps coming back. These four are the ones named in Welcome to the Year; the numbering below is the one the unit pages already use.
| Thread | What it is | Where it starts, and how it grows |
|---|---|---|
| 1. OPVL and AI Documentation | The discipline of evaluating sources, including AI, and documenting honestly how you used tools. | Unit 0 on news and papers, Unit 1 on planetary data and AI output, Unit 2 on government geological surveys, Unit 4 on IPCC projections. Same four letters, harder sources. |
| 2. Systems thinking | The discipline of seeing Earth as interconnected subsystems where changes propagate. | Unit 1 with your first Earth systems diagram, then everywhere: the carbon cycle, the water cycle, a watershed, a neighborhood. |
| 3. Engineering design | The discipline of designing solutions under multi-criteria constraints with honest trade-offs. | Unit 3 is where it becomes the whole task: a fixed budget, real hazards, and three iterations. Units 5 and 6 apply the same reasoning to water and to land use. |
| 4. Science, policy, and the public | The discipline of taking scientific work and translating it for audiences who must act on it. | Unit 2 is the first time you write for a planning audience instead of for school. Units 4, 5 and 6 raise the stakes and sharpen the audience. |
The eight defenses are not a fifth thread. They are the structure all four threads get tested in: one per unit, each in front of an audience that is not your teacher. Defending Your Work covers how they run.
What each unit is trying to get you to be able to say
One sentence per unit. If you can say it in your own words and back it with something you did, you have the unit. Each one also appears on its own unit page, with the three questions that get you there.
Unit 0: Scientific Practices and Class Foundations
- The reliability of a claim depends on the conditions under which it was produced, not on how confident it sounds.
- Disagreement among informed sources marks where evidence is incomplete or where values differ, rather than where someone is simply wrong.
- A tool that produces fluent language is a source like any other, and recording how it was used is what turns its output into evidence a reader can weigh.
Unit 1: Earth and Universe
- Habitability emerges from interactions among a world's systems rather than from any single condition.
- A framework built from known cases becomes an instrument for judging cases its maker has never seen.
- Asking where a condition fails reveals the system that holds it in place.
Unit 2: Surface Processes
- Present landforms record the processes that produced them, so a landscape can be read as evidence of its own history.
- Processes too slow to notice accumulate into the features that constrain what people can build and where.
- The limitations of a measurement are properties of how and when it was taken, not flaws in the thing measured.
Unit 3: Plate Tectonics and Natural Hazards
- A hazard becomes a disaster through the choices a society makes about where and how it builds.
- Designing under a fixed budget allocates limited protection against uncertain events, so every design encodes a judgment about which losses are acceptable.
- The same structure performs differently in different settings, so a design can only be judged against the conditions it will actually meet.
Unit 4: Atmosphere and Climate
- A projection states what follows from a stated set of assumptions, so its worth depends on those assumptions being visible and challengeable.
- A model is a simplification chosen on purpose, and knowing what it leaves out is what makes its output usable.
- A response to a systemic problem either reduces its cause or absorbs its effect, and the level at which a decision is made determines which of those is available.
Units 5 and 6 are taught and both end in a serious piece of work: a stakeholder position defended in a roundtable, and a neighborhood plan whose trade-offs you have to name and quantify. What they do not yet have is the layer above, written down. Unit 7 is not built.
That is stated here rather than quietly left off, because a page like this is only useful if it is honest about where it stops. These will be added when the units carry the same block-level structure the earlier units do.
Three kinds of question
Each unit page carries three questions under its sentence, and they are labeled on purpose. They are not three attempts at the same question. They are a route.
- Factual. Has a findable answer. You can look it up, and you should. This is where the vocabulary and the mechanisms live.
- Conceptual. Asks why the facts behave the way they do. The answer transfers to a case you have not met.
- Debatable. Informed people who know the evidence still disagree. Your job is not to find the answer but to hold a position and say what would change your mind.
If you can only answer the factual one, you know the unit's content. If you can answer all three, you have the unit. The rubric reflects that: K/U rewards the first, T/T rewards the second and third, and C rewards whether any of it reaches a reader.