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Thinking in Diagrams

Chapter 2: Drawing the Boundary

Drafted for Aryeh's edit.

For chapter 2: Drawing the Boundary

Timing

Section titled “Timing”
  • Reading the chapter: about 9 minutes, its 1,340 words of prose at 150 words a minute. Not counted in those minutes: 3 figures, 1 pair, 2 understanding checks, the reading exercise and the exercises.
  • A session: 45 minutes, the exercises set for it. (estimate)
  • Afterwards: 55 minutes, the exercises set for then. (estimate)

Common misreadings

Section titled “Common misreadings”
  • A boundary drawn around an organization chart. The bad diagram’s boundary is the organizing committee, with a part for each officer: who sits on the committee, not what the festival runs. The lab passes it once every exchange is named. In the understanding check about childminding, a nested boundary named Ana names a part for who does it; in SC 05, a self-check has each part named for what it does.
  • One exchange carrying two things, or both directions. An exchange names one thing crossing one way: rent and repairs is two exchanges, in SC 03’s self-check. In the understanding check about childminding, one exchange, childminding is this misreading; in the reading’s second question, the customer’s one line became two exchanges.
  • Exchanges drawn without names. The bad diagram’s five exchanges have none, and the lab’s check lists all five: a line without a name shows that something crosses, not what.
  • A party placed by what it is or where it sits, not by whether the system runs it. In the understanding check about Dev, he’s a nephew and he still sleeps in the spare room are wrong choices; in the reading’s first question, so is only the personal banking customer: the other two are software.
  • What passes between two parties outside drawn as an exchange. In the reading’s second question, the e-mail service’s line to the customer is no exchange and is left out; by CS 02’s self-check, so are the county council’s payments to Dale Coaches.

Exercises to set

Section titled “Exercises to set”

The session runs from one boundary at a person’s scale and at a planet’s to exchanges both ways and the published map; a nation’s exchanges, nested parts and the case come afterwards.

For a session

Afterwards

Sources

Section titled “Sources”