Every line is a sentence.

Start with one question

FOCUS QUESTIONWhat causes Earth's seasons?

A concept map answers one question, called the focus question. Joseph Novak and Alberto Cañas put it plainly: "Every concept map responds to a focus question." This page answers the one above, twice. First the way many people would, then the corrected way.

A first map

Here's a common first answer, drawn as a concept map. Each box is a concept. Each line has linking words on it. Read along the arrow, from one box to the next, and every line makes a sentence:

Each sentence is a claim you can check, and three of these fail. NASA's Space Place says it directly: "Earth's distance from the Sun is not the cause of the seasons." Earth is actually closest to the Sun in early January, in the middle of the Northern Hemisphere's winter.

The map didn't need an outside source to show the problem, though. The cross-link between the two hemispheres is true, and it can't be true if distance were the cause.

The corrected map

The same question, answered again. The cause moves to the top, and every line is still a sentence:

NASA puts the cause in one line: "Earth's tilted axis causes the seasons." When a hemisphere leans toward the Sun, sunlight hits it "more directly," and the National Weather Service adds that "the high sun angle produces long days." Both mean more heating. Distance is still on the map, joined by cross-links that say what it does and doesn't do.

The numbers beside two concepts are examples, not concepts, so they sit outside the boxes. The axis is tilted 23.44 degrees, and Earth's distance from the Sun runs from about 147 to 152 million km over the year (NASA's Earth Fact Sheet). Two concepts that may belong wait in the parking lot.

How a concept map works

Novak developed concept maps in 1972, in a research program at Cornell that followed how children's understanding of science changed. In their report on the method, Novak and Cañas define the parts:

• Concepts, usually in boxes. A concept is "a perceived regularity in events or objects, or records of events or objects, designated by a label."
• Linking words on the lines. They "specify the relationship between the two concepts."
• Propositions: two or more concepts joined by linking words "to form a meaningful statement." Each one is a sentence that's true or false.
• A hierarchy, with "the most inclusive, most general concepts at the top of the map and the more specific, less general concepts arranged hierarchically below."
• Cross-links between branches, which "help us see how a concept in one domain of knowledge represented on the map is related to a concept in another domain."
• A parking lot: the list of concepts not yet placed, "since we will move these concepts into the concept map as we determine where they fit in."

The linking words are the hard part, and the useful one. "Students often comment that it is hard to add linking words onto the 'lines' of their concept map," the report says. "This is because they poorly understand the relationship between the concepts." A map with bare lines can hide a wrong idea. A map where every line is a sentence can't. That's why, in Novak and Cañas's words, concept maps are "effective in identifying both valid and invalid ideas held by students."

A concept map isn't the C4 model, which is a notation for software systems at levels of zoom. It answers one focus question, on any subject, with sentences. It isn't Gestalt grouping or progressive disclosure either: those decide how a picture is grouped and when to show more. A concept map decides what you claim, one sentence at a time.

Watch a map get checked

The clip builds the first map, reads each line as a sentence, and then adds one cross-link. Watch what that cross-link does to the line above it.

Check every sentence

A concept map is only as good as its sentences. This page lists every one it makes, and checks the map's other parts each time it's built:

Map this way

1. Write the focus question. One question the map must answer. Put it at the top.
2. List the concepts. Novak and Cañas suggest 15 to 25 for a full map. Rank them from most general to most specific. That list is your parking lot.
3. Place the most general concept at the top. Bring in concepts below it as you find where they fit.
4. Put linking words on every line. Read the line out loud as a sentence. If you can't, the link isn't clear yet.
5. Add cross-links. Look for relationships between branches. They're often where a wrong idea shows up.
6. Check every sentence. Is it true? Does it help answer the focus question?
7. Revise. "A concept map is never finished," Novak and Cañas write. Good maps take several passes.

Ask your agent

Make a concept map (Joseph Novak's method) that answers the focus question below.
1. Restate the focus question at the top.
2. List 10 to 20 concepts, from most general to most specific. Concepts are short labels, not sentences.
3. Build the map: put the most general concept at the top, and join concepts with linking words on every line. Mark at least two cross-links between branches.
4. Output the map twice: first as a numbered list of propositions, each one a full sentence (concept, linking words, concept), with cross-links marked; then as Mermaid or Graphviz (DOT) code, with the linking words as edge labels.
5. Put any concept you couldn't place in a "parking lot" list.
6. Don't add facts you aren't sure of. If a proposition depends on something you'd need to check, mark it "to check".
Then ask me which propositions I think are wrong, and fix the map from my answers.

Focus question:
[paste here]

What good output looks like: every numbered sentence reads true on its own, and you can point at the one you disagree with.