Hands-on Activity
Decompose a sandwich
The classic decomposition activity — and a fast way to surface hidden assumptions.
Setup
Each participant writes complete instructions for making a sandwich. Give five minutes and no further guidance — ambiguity in the prompt is intentional.
Running the activity
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Write
Five minutes, working individually. Participants write instructions for making a sandwich.
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Swap
Partners exchange papers and mark every step that could be misread or that assumes something not stated.
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Discuss
Pairs compare what they each assumed. "Put the peanut butter on the bread" — which side? How much? With what?
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Revise
Rewrite with the assumptions made explicit. Notice how much longer the instructions become.
Debrief questions
- Which assumption surprised you most?
- How much longer was the revised version?
- Where is the line between precise and unusable?
- How does this connect to writing instructions for a computer?