10.3 Small Group · Group 2
Tier 1 Extension · Non-Routine Synthesis · Misconception Traps · Rigorous CER Proofs
puzzle · pattern · Procedural Fluency · Reasoning & Critique
- 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.
- Before moving anything, I describe what the solved puzzle will look like: the discs in the same order — smallest on top to largest on bottom — but on a different rod.
- Then I play the small cases: a one-disc tower takes 1 move, and a two-disc tower takes 3 moves.
- A three-disc tower takes at least 7 moves. Small cases are how mathematicians play.
- Discs: 1, 2, 3 — Steps: 1, 3, 7. What is happening from each row to the next?
- Double the number of steps and add 1: 1 doubled plus 1 is 3, and 3 doubled plus 1 is 7.
- So 4 discs take 7 × 2 + 1 = 15 steps, and 5 discs take 15 × 2 + 1 = 31 steps.
- The pattern just solved a puzzle we never touched.
- 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 ___ ."
- puzzle (rompecabezas) — A problem designed to be played with — it has rules, a goal, and room to imagine solutions.
- pattern (patrón) — Something that repeats or changes in a predictable way.
- pattern rule (regla del patrón) — A rule that tells you how to get the next value in a pattern from the one before it.
- predict (predecir) — To say what will happen before it happens, using a pattern or reasoning.
- organize (organizar) — To arrange information — often in a table — so patterns become easier to see.
- Doubling the previous number of steps but forgetting to add 1 — answering 14 instead of 15 for four discs, or 30 instead of 31 for five.
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1 FILL TABLE
Use the doubling pattern to complete the table of fewest moves.
Discs Pattern: double the previous, add 1 Fewest moves 3 4 6 ✏️ Scratchpad / Reasoning -
2 MATCHING GAME
Match each tower to the calculation that gives its fewest moves.
- 4-disc tower
- 5-disc tower
- 6-disc tower
- Any n-disc tower
- A2 × 7 + 1 = 15
- B2 × 15 + 1 = 31
- C2 × 31 + 1 = 63
- DDouble the (n − 1)-disc answer, add 1
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3 MULTIPLE CHOICE
Why is finding a pattern MORE powerful than just solving the three-disc puzzle by hand?
- AThe pattern predicts the answer for towers you have never played, like five or six discs
- BThe pattern lets you skip the rules of the puzzle
- CPatterns make the discs move by themselves
- DA pattern proves the puzzle is impossible
✏️ Workspace & Solution Steps -
4 MULTIPLE CHOICE
Will the fewest number of steps for a Tower of Hanoi puzzle always be an ODD number?
- AYes — doubling any whole number gives an even number, and adding 1 makes it odd
- BNo — every other tower size gives an even number of steps
- CYes — but only because 7 happens to be odd
- DNo — the steps alternate between odd and even
✏️ Workspace & Solution Steps -
5 MULTIPLE CHOICE
A five-disc tower takes 31 steps. Using the pattern rule, how many steps would a SIX-disc tower take?
- A63 steps
- B62 steps
- C36 steps
- D32 steps
✏️ Workspace & Solution Steps
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6 OPEN RESPONSE
Before solving, the lesson asked you to DESCRIBE what the solution will look like. Why is imagining the ending a useful way to start a puzzle?
✏️ Mathematical Justification & Response
Complete each sentence stem to demonstrate precise mathematical reasoning:
Writing Task: Justify why your mathematical solution is accurate and complete.