On your desk: six paper shapes — two squares, two triangles, a circle, and a long strip. Behind a folder, where your partner cannot see it: a card showing those six shapes arranged into a particular figure. Your partner has the same six shapes and no idea what the figure looks like.
You may not draw it for them. You may not point. Once the run starts you may not speak. All they get is what you wrote down.
The task
Write a numbered list of instructions that gets your partner from six loose shapes to your exact figure. Hand the list over and then go silent — no hints, no eyebrows, no helpful noises. Your partner follows your words literally and only your words: the most absurd reading a sentence permits is the reading it will get, because that is how a machine reads.
Then lift the folder and compare the two figures.
Three rules make it work:
- The executor is literal, and silent. No questions, no guessing at intent. If step 4 says “put the triangle on top”, any triangle, any “on top”, is fair.
- The author is silent too. Watching your own instructions fail without being able to intervene is the entire point.
- No edits mid-run. Write down what went wrong instead. That list is your real product today.
Round two
Swap partners, revise your list, and run it again with somebody who has never seen the figure. Version two is almost always shorter as well as more precise, which is worth arguing about: why does saying it better take fewer words rather than more?
Facilitation notes
Materials. Six card shapes per student, cut from one template so every set is identical, plus one figure card per author (four or five different figures is plenty — reuse them). Envelopes keep sets from merging.
Timing in a 70-minute period. Five minutes to set up and explain the three rules; ten to write; ten to run and compare; ten to debrief round one; ten to revise; ten to run round two; the rest for the consolidation that leads into What a Program Is.
Say this, not that. Resist “be more specific” — it teaches nothing. Instead ask, at the desk: “Which triangle did you mean? Where exactly is ‘above’? What if the strip is already there?” Let the executor’s literalness do the teaching.
Common failure modes, all useful. Undefined nouns (“the shape”); undefined positions (“beside”, “a bit up”); missing starting state (the desk is never cleared); missing units (“halfway” — of what?); and the assumption of shared context (“like the one on the board”).
The trap worth planting. Give one or two authors a figure where two shapes overlap. Overlap forces order-of-operations language, and that group will hand the class the word sequence for free.
If a pair finishes early: ask them to write the shortest list that still works, and then the shortest list that would still work if the executor were a very tired person at the end of a long day. The second list is longer. Ask them why.
What tends to surface
Somewhere between “put the square down” and “which square?”, the room works out what an instruction actually is: a sentence that survives its worst reading. Sequence appears (step 3 assumed step 2 happened), naming appears (you cannot refer to something you never named), and the gap between what you meant and what you said stops being a joke about computers and becomes a description of your own writing.
The other discovery is quieter. The best lists in the room are not the cleverest ones. They are the ones written by somebody who pictured a real person on the other side of the folder — the first appearance of the question this whole course is built on, which Who Is This For takes up properly.
Where this goes next
Tomorrow the executor is a machine that is even more literal than your partner and considerably less forgiving, and the words are Python. The name for what you wrote today, and for what a computer does with it, is in What a Program Is. The habit of writing down what went wrong, rather than fixing it in the moment, becomes Testing and Debugging in about a week.
The answer is not on this page
There is no model instruction list here, and there is no figure that “works”. Every class produces different disasters, and the disasters are the curriculum. What your room decides an instruction must contain, your room will decide together — one lopsided paper figure at a time.
Curriculum connection
B3.1
design simple algorithms (e.g., add data to a sorted array, delete a datum from the middle of an array) according to specifications;
Link to original
B2.2
use appropriate vocabulary and mode of expression (i.e., written, oral, diagrammatic) to describe alternative program designs, and to explain the structure of a program;
Link to original