10.5 Small Group · Group 2
Tier 1 Extension · Non-Routine Synthesis · Misconception Traps · Rigorous CER Proofs
repetition · pattern · Procedural Fluency · Real-World Applications
- You already can do this. So we go up a level, not up a number: find what is always true, show it a second way, and be ready to defend it with a reason instead of an answer.
- A border repeats: pink circle, purple square, blue triangle, pink circle, purple square, blue triangle, ...
- The pattern unit is 3 shapes long: circle, square, triangle.
- To predict shape number 12, I divide: 12 ÷ 3 = 4 with no remainder, so shape 12 ends a complete unit — it is the blue triangle.
- The next three shapes after any complete unit will be a pink circle, a purple square, and a blue triangle.
- The pattern unit is still 3 shapes long.
- 20 ÷ 3 = 6 complete units with a remainder of 2, because 6 × 3 = 18 and 20 − 18 = 2.
- A remainder of 2 means shape 20 is the second shape in the unit.
- The second shape is the purple square.
- Now prove it: say why that move had to work at all — not just that it did.
- Sentence frame — convince a skeptic: "My method works because ___ . It would stop working if ___ ."
- repetition (repetición) — The same object, shape, or form repeated multiple times.
- pattern (patrón) — A set of objects or shapes that are repeated and arranged in a regular order.
- pattern unit (unidad del patrón) — The smallest chunk of a pattern that repeats.
- rhythm (ritmo) — A design element created by varying the placement, size, orientation, or order of the same objects or shapes.
- predictability (previsibilidad) — Being able to know what comes next because the design follows a rule.
- Calling every repeated design a 'pattern.' One identical shape repeated is repetition; a pattern needs a unit of shapes repeating in a regular order; and rhythm varies the shapes' size and order, so it is neither.
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1 FILL TABLE
The border pattern repeats circle, square, triangle. Name the shape at each position.
Position number Thinking with the unit of 3 Shape 7 12 20 ✏️ Scratchpad / Reasoning -
2 MATCHING GAME
Match each vertex arrangement to its angle sum — and what it means for tessellation.
- 4 squares at a vertex
- 6 equilateral triangles at a vertex
- 3 regular hexagons at a vertex
- 3 regular pentagons at a vertex
- A4 × 90° = 360° — no gaps
- B6 × 60° = 360° — no gaps
- C3 × 120° = 360° — no gaps
- D3 × 108° = 324° — a gap remains
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3 MULTIPLE CHOICE
How is a design with rhythm different from a pattern?
- ARhythm varies size, orientation, and order, so it often lacks predictability; a pattern repeats in a regular order
- BRhythm uses shapes and a pattern does not
- CA pattern varies its shapes and rhythm never does
- DThere is no difference between them
✏️ Workspace & Solution Steps -
4 MULTIPLE CHOICE
The circle-square-triangle pattern continues. What is shape number 25?
- AThe pink circle
- BThe purple square
- CThe blue triangle
- DThere is no shape 25
✏️ Workspace & Solution Steps -
5 MULTIPLE CHOICE
Which element of geometric design often LACKS predictability?
- ARhythm
- BRepetition
- CPattern
- DThe pattern unit
✏️ Workspace & Solution Steps
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6 OPEN RESPONSE
If a new row of circles were added to the rhythm painting, what would they look like? Explain your thinking.
✏️ Mathematical Justification & Response
Complete each sentence stem to demonstrate precise mathematical reasoning:
Writing Task: Justify why your mathematical solution is accurate and complete.