6.13 Small Group · Group 2
Second Challenge Form · Non-Routine Extension · Same Standard, New Problems
Prime Factorization · Prime number · 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.
- I want the prime factorization of 60. I start by splitting it: 60 = 6 × 10.
- 6 is not prime, so I break it: 6 = 2 × 3. Both 2 and 3 are prime, so I stop those branches.
- 10 is not prime, so I break it: 10 = 2 × 5. Both 2 and 5 are prime, so I stop.
- Now every factor is prime: 60 = 2 × 2 × 3 × 5.
- Using exponents, I write it as 2² × 3 × 5. I check: 2 × 2 × 3 × 5 = 60. Correct.
- Let's factor 12 together. What is one way to split 12 into two factors? (You might say 3 × 4.)
- Is 3 prime? Yes, so we keep it. Is 4 prime? No — what is 4 split apart? (4 = 2 × 2.)
- So put the prime factors together: 12 = 2 × 2 × 3. Every factor is prime, so we are done.
- 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 ___ ."
- Prime Factorization (Factorización prima) — Writing a whole number as a product of only prime numbers.
- Prime number (Número primo) — A number bigger than 1 that you can only divide by 1 and itself.
- Composite number (Número compuesto) — A number bigger than 1 that you can divide by more than just 1 and itself.
- Factor (Factor) — A factor of a whole number divides it evenly, with no remainder. For example, 3 is a factor of 12 because 12 ÷ 3 = 4.
- Factor tree (Árbol de factores) — A picture that splits a number into its prime numbers, step by step.
- Exponent (Exponente) — A small number that tells how many times to multiply a number by itself.
- A common mistake in Prime Factorization is stopping the factor tree too soon — leaving a composite number like 4, 6, 8, or 9 in the final answer instead of continuing to split it. For example, writing 20 = 4 × 5 as the prime factorization (4 is composite) instead of finishing with 20 = 2 × 2 × 5. Before you submit, check every number in your final answer: if any factor can still be broken into smaller factors, the tree isn't finished yet.
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1 MULTIPLE CHOICE
Two students found different factor trees for 60. Student A started with 2 × 30. Student B started with 6 × 10. Which statement is true?
- ABoth get the same prime factorization: 2 × 2 × 3 × 5
- BOnly Student A gets the correct prime factorization
- COnly Student B gets the correct prime factorization
- DThey will get different prime factorizations
✏️ Workspace & Solution Steps
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2 MULTIPLE CHOICE
Which of the following is a prime number?
- A17
- B15
- C21
- D9
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
What is the prime factorization of 30?
- A2 × 3 × 5
- B5 × 6
- C2 × 15
- D3 × 10
✏️ Workspace & Solution Steps
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4 ERROR ANALYSIS
Fix our table's thinking
- 1The problem:The first lock panel shows 90. What is the prime factorization of 90?
- 2A classmate at our table answered:2 × 45
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation -
5 ERROR ANALYSIS
Spot the Common Mistake
- 1Find the prime factorization of 45, using exponents:Start: 45
- 2First split:45 = 5 × 9
- 3Break down 9:9 = 3 × 3, so 45 = 5 × 3 × 3
- 4Write with exponents:45 = 3² × 5²
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation -
6 ERROR ANALYSIS
Find Marcus's Mistake
- 1Find prime factorization of 48:Start: 48
- 2First split:48 = 6 × 8
- 3Break down 6:6 = 2 × 3
- 4Break down 8:8 = 2 × 4
- 5Final answer:48 = 2 × 3 × 2 × 4
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation
Writing Task: Justify why your mathematical solution is accurate and complete.