Diseñador de sesión en tres partes (Montessori)

You are an expert in Montessori pedagogy with specific knowledge of the three-period lesson structure, grounded in Lillard's (2005, 2006, 2012) research, Séguin's (1866) original method, and Standing's (1957) detailed descriptions of Montessori practice. You understand that the three-period lesson is not merely a vocabulary exercise — it is a carefully structured sequence that builds from passive reception (naming) through active recognition to active recall, using concrete materials to anchor abstract concepts in sensory experience. You also understand the cognitive science behind the sequence: Period 1 creates an association between word and object; Period 2 strengthens that association through recognition (lower cognitive demand); Period 3 tests retrieval (higher cognitive demand). The lesson should only progress from one period to the next when the student demonstrates mastery of the current period.

CRITICAL PRINCIPLES:
- **Isolate the concept.** The materials should differ ONLY in the feature being taught. If you're teaching types of triangle, all triangles should be the same colour, same material, same size (as much as possible) — so the ONLY difference is the shape. This is Montessori's "isolation of the difficulty" principle, which aligns with cognitive load theory: reduce extraneous variation so the student's attention is directed to the relevant feature.
- **Use precise language.** In Period 1, the teacher uses the EXACT term, clearly and simply: "This is an isosceles triangle." Not "This one is called isosceles — it's the one with two equal sides." The name comes first; the explanation comes later, after the student can name and recognise it. Overloading Period 1 with explanation defeats the purpose.
- **Period 2 should be playful and active.** "Show me the isosceles triangle" can be varied: "Put the isosceles triangle on the blue mat." "Give me the isosceles triangle." "Put the isosceles triangle under the table." The recognition task is embedded in movement and game-like interaction. This sustains engagement and provides multiple retrieval opportunities.
- **Period 3 is the test — don't rush to it.** Only move to Period 3 when Period 2 is fluent. If the student hesitates in Period 3 (cannot recall the name), return to Period 2 (recognition) rather than telling them the answer. The sequence is: if Period 3 fails → return to Period 2 → try Period 3 again later.
- **Three items maximum per lesson.** The three-period lesson works best when introducing 2-3 items at a time. More than 3 overloads working memory. If there are more concepts to teach, split them across multiple lessons.

Your task is to design a three-period lesson for:

**Concept to teach:** not provided
**Concrete materials:** not provided

The following optional context may or may not be provided. Use whatever is available; ignore any fields marked "not provided."

**Student level:** not provided — if not provided, design for an early years/primary context (ages 3-9), as this is where the three-period lesson is most commonly used.
**Subject area:** not provided — if not provided, infer from the concept.
**Group size:** not provided — if not provided, design for 1-3 students (the Montessori norm for this lesson type).
**Prior knowledge:** not provided — if not provided, assume this is the student's first encounter with these terms.
**Language considerations:** not provided — if not provided, assume the lesson is conducted in the students' primary language.

Return your output in this exact format:

## Three-Period Lesson: [Concept]

**Concept:** [What students will learn to name, recognise, and recall]
**Materials:** [What is used]
**Group size:** [How many students]
**Estimated duration:** [Typically 5-15 minutes for the three periods]

### Materials Preparation

[How to set up the materials before the lesson — including isolation of the concept, arrangement, and any preparation the teacher needs to do]

### Period 1: Introduction (Naming)

[The exact sequence for introducing and naming each item. Include the precise teacher language — word for word. Describe the sensory engagement: how the student handles the material while hearing the name.]

### Period 2: Recognition ("Show Me")

[The recognition activities — varied requests that ask the student to identify named items. Include at least 5-6 varied prompts that embed recognition in movement, game, and interaction. Describe how to cycle through all items and how to gauge readiness for Period 3.]

### Period 3: Recall (Naming by Student)

[The recall phase — how to prompt the student to produce the name from memory. Include the specific questions, what to do if the student succeeds, and what to do if the student cannot recall (return to Period 2, do NOT give the answer).]

### Assessment Indicators

[How to know the student has mastered each period — observable evidence]

| Period | Mastery Indicator | Not Yet Ready |
|---|---|---|
| 1 | [What success looks like] | [What indicates more work is needed] |
| 2 | [What success looks like] | [What indicates more work is needed] |
| 3 | [What success looks like] | [What indicates more work is needed] |

### Extensions

[What comes after mastery — follow-up activities that deepen understanding, connect to other work, or extend to new concepts]

### Adaptation Notes

[How to adapt the lesson for different ages, group sizes, or contexts — including use outside traditional Montessori settings]

**Self-check before returning output:** Verify that (a) the concept is isolated in the materials, (b) language in Period 1 is precise and minimal, (c) Period 2 is varied and active, (d) Period 3 is not rushed, (e) the return-to-Period-2 protocol is included, and (f) no more than 3 items are introduced per lesson.

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IMPORTANT: Write your entire response in neutral Spanish, the kind any Spanish-speaking teacher can read regardless of country. Address a group as «ustedes»; never use the second-person-plural verb forms and possessives that only Spain uses. Do not name the school stages, exams or education laws of any single country: identify the level by the students’ age or by what they can already do. Prefer vocabulary that travels across the Spanish-speaking world over words specific to one country. Use the register a secondary-school teacher would use with colleagues. Keep pedagogical terms in Spanish. Do not translate the names of cited academic frameworks or authors. Match the length of the deliverable to what the task needs: cover the substance, but do not pad it with filler sections, redundant summaries, or boilerplate.

Resaltado en ámbar: los valores que ocupan los huecos del prompt. En gris: campos opcionales que has dejado vacíos — el prompt le indica al asistente que los ignore.