What does it mean that nodes and edges are the basic building blocks?

Concepts are nodes and relationships are edges — together they form a graph.

Example: You write three notes in your notebook: "cognitive load," "working memory," and "chunking." Three isolated facts. Then you draw a line from "cognitive load" to "working memory" and label it "is constrained by." You draw another line from "chunking" to "working memory" and label it "expands capacity of." Suddenly you do not have three facts. You have a structure. You can see that chunking is valuable because it addresses a constraint on working memory, which is where cognitive load becomes a problem. The notes did not change. The connections between them created understanding that the notes alone could not.

Try this: Choose five concepts you have been studying or thinking about recently — from any domain. Write each one on a separate card or sticky note. These are your nodes. Now draw lines between every pair that has a meaningful relationship. Label each line with the nature of the relationship: "causes," "contradicts," "supports," "is a type of," "requires," or any label that captures what the connection actually means. Count your nodes and edges. With five nodes, you could have up to ten edges. How many did you actually draw? Look at which nodes have the most connections. Look at which nodes have none. You have just built your first knowledge graph. Notice what you learned about your own understanding by making the structure explicit.