Build the first instrument#

Two choices in building this ladder#

Week 2 used recognition to mean a feeling of familiarity. Rung 1 now requires an observable recognition response; that is limited evidence, not the feeling alone. Application and connection were candidate performances in our plan. Here we judge them through the defined rungs—for example, explaining a new case or justifying a connection—rather than making them separate rungs.

Retrieve your Week 4 rule · 2 minutes#

Bring back the sentence “I counted that as stronger evidence because…” exactly as you wrote it. After learning the seven rungs, identify the rung your rule rewards and one performance it cannot distinguish. Preserve the original, then write a revised rule. If you have no record, use this provisional rule: “I counted a correct answer without the reference as stronger evidence.”

Worked comparison#

The fallback rule rewards source removal but cannot distinguish Recall from Reconstruction: both can happen without a reference. A revised rule could require the relations between parts to be rebuilt, not just the parts named. Resource conditions still belong in the record. A different original rule may map to a different rung; explain the match.

How to use this lesson#

Read at your own pace; no presenter is needed. Allow around 40 minutes. Have somewhere to write a few short answers.

At a Pause slide, attempt the task before advancing. The next slide or two explain the reasoning so you can compare it with yours.

You need nothing from Weeks 1–4 open in front of you — every performance this lesson uses is quoted again here. Sam, Theo, Priya and Rowan are the fictional people those weeks already introduced; nothing new is invented about any of them today.

Where Week 4 left us#

Week 4 gave one person, Rowan, three performances on one lock under three conditions. Two careful readers could reach opposite verdicts from the same texts, with no way to show each other where they went wrong.

It ended by naming what was missing: not more evidence, but a rule for weighing the evidence already in hand — written down before you look, so it can be inspected and argued with.

A loose preview, now made precise#

Week 4 previewed this loosely, as a ladder running “from recognising something up to connecting it to other things.” That phrase was a placeholder.

Naming the actual top rung was this week’s job, not last week’s. Here is the precise version.

What an instrument is#

An instrument is a stated rule for turning a performance into a judgement, written before you look at the case it will be applied to.

It is not a theory of what understanding is. It makes no claim about what happens inside a learner’s head.

It is a tool for making your own judgement inspectable — so a disagreement can be about which rung applies, not about who sounded more convincing.

You have already used two#

Week 1’s evidence record — Observation, Interpretation, Limit — was a small instrument.

Week 3’s four-letter scheme — Part, Relation, Causal step, Condition omitted — was a second one, built for one kind of performance.

This week’s ladder is broader: one scale for almost any performance the course produces from here on.

Rung 1 — Recognition#

“I’ve seen this.”

The person correctly matches or repeats something already stated, with it available to consult or freshly in view.

The weakest rung: it requires identifying, not producing.

Rung 2 — Recall#

“I can retrieve this without the source in front of me.”

The person produces a specific piece of material — a term, a fact, a step — from memory, with nothing to consult.

Recall returns material. It does not yet require that material to be correctly related to anything else.

Rung 3 — Reconstruction#

“I can rebuild the relationships between the parts.”

Week 3’s definition, unchanged: naming the parts, placing them relative to one another, giving the causal steps — without the source in view.

A list of correct terms with nothing joining them is Recall, not Reconstruction.

Rung 4 — Explanation#

“I can make this intelligible to someone else.”

The person produces the structure for an audience: recast, ordered, pitched so that another person — not just the explainer — could follow it.

A different demand from Reconstruction, which only has to satisfy the person producing it.

Rung 5 — Justification#

“I can support the claims inside my explanation.”

Not only asserting a causal step, but giving the reason it holds — the “because” a listener could doubt and ask about.

An explanation can be complete and still stop short of this.

Rung 6 — Challenge#

“I can respond when someone attacks my assumptions, evidence or relationships.”

Someone else raises a specific objection, and the person answers it — by defending, revising, or showing why the objection misses.

This rung cannot be produced by a person working alone.

Rung 7 — Boundary#

“I know where my explanation stops working.”

The person names, unprompted, a condition under which their own account would fail, become uncertain, or need to be checked.

The edge of their own model, found by looking — not told by someone else.

The seven rungs are this course’s own construction, built for this course’s question — not drawn from Bloom’s taxonomy or any other published scale.

Two things the ladder is not#

Not strictly ordered. A performance can show Boundary-level awareness without ever cleanly showing Justification.

Not a checklist. A short technical question may have no occasion for a Challenge or a Boundary at all — that is not a failure of the person answering.

Treat the rungs as seven kinds of evidence, not seven steps everyone must climb in order.

It is also not settled#

Later weeks attack assumptions built into this ladder. This week names one of them. Week 12 attacks the ladder itself, once you have used it for a term.

A course that presented its own instrument as finished would be doing the thing it exists to criticise.

A. Sam — Week 1#

Reading the reference with it open:

“Wi-Fi and internet access are different.”

B. Theo — Week 2#

Writing from memory, nothing in front of him:

“The slider pulls the two sides of teeth together and they interlock like fingers. Pulling it back down separates them again.”

C. Priya — Week 3#

Reconstructing the lock from memory:

“A door lock has a barrel that turns when you put the right key in. Inside there are pins of different heights. The key pushes the pins up to the right heights, and then the barrel can turn and the door opens. A wrong key does not push them to the right heights, so it will not turn.”

D. Rowan — Week 4, condition (b)#

Explaining to a novice, reference closed:

“Every pin is a different length and every notch is a different depth. The right key lifts each pin by exactly its own amount, so all of them come flush with that join at the same moment.”

E. Rowan — Week 4, condition (c)#

Predicting an unfamiliar case:

“I think it does not matter that the other five are fine. One is enough. Because the barrel is one piece… Would you even be able to tell this key from a totally wrong one, from the outside? I do not think you would. That feels wrong to me but I cannot see what would make it false.”

Worked response: A — Sam#

A strict reading holds him at Recognition: the source was open, and repeating a stated sentence with it in view does not yet require retrieving anything unaided.

A looser reading calls it Recall — Sam produced the sentence rather than pointing at it.

The disagreement turns entirely on whether “the source was available” changes which rung applies, or only how much we trust reaching it. Hold that question; a later slide comes back to it.

Worked response: B — Theo#

The task he attempted was Explanation — nothing in front of him, for a lesson that assumed a naive reader.

Whether his performance reaches it is separate. His sentence names an outcome (“they interlock like fingers”) without the mechanism that produces it, and omits what holds one tooth to the next.

A generous reading credits Recall — real, correct material, retrieved. The missing causal step is exactly what Explanation requires, and his sentence does not supply it.

Worked response: C — Priya#

She attempted Reconstruction — nothing in front of her, asked to rebuild relationships, not list terms.

Her performance is thin at exactly the place Reconstruction is defined: four parts missing, and the one relation she states (“right heights, so it turns”) is a rule with no mechanism behind it.

Scored by task attempted: Reconstruction. Scored by what actually got reconstructed: closer to Recall. Both readings are defensible.

Worked response: D — Rowan (b)#

Explanation by task — source-free, pitched for a novice — and it is fluent, complete in outline, and wrong in one place: the two-pin stack has collapsed into a single pin.

This shows more than Theo’s — structure, an audience, independent phrasing — and it still misdescribes the mechanism.

Reaching a rung is not the same as reaching it accurately. The ladder tells you what kind of evidence you have, not whether that evidence is good news.

Worked response: E — Rowan (c), part one#

“…because the barrel is one piece” — a reason for a claim. This is Justification: it says why, not just that.

”…I cannot see what would make it false” — Rowan naming, unprompted, the edge of what this performance can show from the outside. This is Boundary.

Worked response: E — Rowan (c), part two#

Notice what is missing in between: nothing here is Challenge. Nobody attacked Rowan’s account and made them defend it — the hedged opening (“do you want me to guess?”) is uncertainty about the genre of the task, not a challenge.

One performance touches rungs 5 and 7 without passing through 6. “Not strictly ordered,” demonstrated rather than asserted.

Why that gap matters#

Challenge cannot be produced by a person working alone, however hard they think about their own account. It needs a second party who has not already agreed with them.

An instrument that only measures what a solo performance can supply is missing a whole rung. The course will need an activity that specifically manufactures one.

Worked response: meeting the Challenge#

Using the lock: a correctly working key already has to get every stack level with the shear line, and a wrong key fails as soon as one stack is off. Two wrong stacks do not make the lock “twice as locked” — it was already fully stopped by the first one.

The attack is answered by a fact Week 4 already established: the plug is one object, not five independent ones, so failures do not add up, they duplicate a verdict the first failure had already reached.

What made that a real response#

Restating your original explanation more firmly is not a response to a Challenge. This one does real work against the objection.

Notice it reuses Rowan’s condition (c) reasoning: once you have the “one object, not five” relation, several objections answer themselves the same way. A good Justification is often the raw material several Challenges are answered with.

Naming the assumption#

A performance produced with a reference open cannot, by this wording, count as Recall or Reconstruction at all — however accurate it is.

The assumption: a performance produced without support is intrinsically stronger evidence than the same performance produced with support.

This week is not the place to defend or attack it. Only to name it.

Where you already met it#

Section on Sam already turned on exactly this question: does the source’s presence change which rung applies, or only how confidently we trust reaching it?

Next week attacks the assumption directly: does needing support show that you do not understand — or only that you were allowed to use what was available?

Keep a short record#

Write four lines and keep them:

1. Rung reached — the highest rung a performance of yours reaches, honestly assessed.
2. Contested case — which of the five you placed differently, and why.
3. The missing rung — one sentence on why Challenge cannot be produced alone.
4. The hidden assumption — restate it in your own words.

If you agreed with every worked placement, go back and argue the other side of one before moving on.

Read further: the ladder’s sources#

Rozenblit & Keil (2002). Cognitive Science 26(5), 521–562. Weeks 2 and 3 used this for the gap between a fluent explanation and a complete one. Rungs 4 and 5 make that same gap into two separately checkable claims. Read the full text.

Clark & Chalmers (1998). “The Extended Mind,” Analysis 58(1), 7–19. Before Week 6: read their case that a resource can participate in thinking rather than merely assist it, and ask which rungs that would change. Read the paper.

Both readings do new work for this week’s question; neither is required to complete the lesson.

What to take from Week 5#

The ladder makes disagreement inspectable. You can now say exactly which rung you placed a performance at, and someone else can argue you out of it — which Week 4 could not do.

It has not made judgement automatic. It has a specific, named assumption sitting inside two of its own rungs.

Next week holds a mechanism fixed and changes only what a person is allowed to consult — testing whether needing support is evidence against understanding, or evidence of nothing at all.

Sources and your next step#

Sam, Theo, Priya and Rowan and every quoted performance above are the same fictional teaching examples earlier weeks used; nothing new is invented about them here.

For the classification exercise and the Challenge-rung task with a record to keep, open the Week 5 investigation. The lecture notes offer a continuous reading version.