6.4 Small Group · Group 2
Second Challenge Form · Non-Routine Extension · Same Standard, New Problems
Write and Evaluate Numerical Expressions with Exponents · Numerical expression · 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.
- Sofia buys 2 member tickets at $15, 4 non-member tickets at $20, and 8 student tickets at $2 each. I write one expression for each ticket type: 2 × 15, 4 × 20, and 8 × 2.
- The whole order is the three costs added together: 2 × 15 + 4 × 20 + 8 × 2.
- Now I evaluate. There are no grouping symbols and no powers yet, so multiplication comes first, left to right: 30 + 80 + 16.
- Then I add: 30 + 80 + 16 = 126. The tickets cost $126.
- Suppose the student tickets cost 2³ dollars each instead of $2. The expression becomes 2 × 15 + 4 × 20 + 8 × 2³.
- Powers come before multiplying, so evaluate 2³ first: 2 × 2 × 2 = 8.
- Now multiply, left to right: 30 + 80 + 64.
- Then add: 30 + 80 + 64 = 174. The order now costs $174.
- 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 ___ ."
- Write and Evaluate Numerical Expressions with Exponents (Escribir y evaluar expresiones numéricas con exponentes) — Turning a situation into a number sentence without an equal sign, then finding its value in the correct order.
- Numerical expression (Expresión numérica) — A math phrase built from numbers and operations, with no equal sign and no variable.
- Evaluate (Evaluar) — To find the single value an expression is worth by carrying out its operations in order.
- Order of operations (Orden de las operaciones) — The agreed order for evaluating: grouping symbols, then exponents, then multiply and divide left to right, then add and subtract left to right.
- Power (Potencia) — A short way to write repeated multiplication of the same factor, such as 2³ for 2 × 2 × 2.
- Base (Base) — In a power, the number being multiplied by itself. In 2³ the base is 2.
- A common mistake with powers is multiplying the base by the exponent: reading 3² as 3 × 2 = 6 instead of 3 × 3 = 9. A second is evaluating strictly left to right, so 3 + 4 × 2 becomes 14 instead of 11. The order of operations exists so one expression has exactly one value: grouping symbols, then powers, then × and ÷ left to right, then + and − left to right.
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1 MULTIPLE CHOICE
What does 2³ mean?
- A2 × 2 × 2
- B2 × 3
- C3 × 3
- D2 + 2 + 2
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
Sofia buys 4 tickets at $20 each and 2 tickets at $15 each. Which expression shows the total?
- A4 × 20 + 2 × 15
- B4 + 20 + 2 + 15
- C(4 + 2) × (20 + 15)
- D4 × 2 + 20 × 15
✏️ Workspace & Solution Steps
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3 MULTIPLE CHOICE
What is the total of 2 × 15 + 4 × 20 + 8 × 2³?
- A174
- B126
- C210
- D1,392
Show each partial product, then add them -
4 MULTIPLE CHOICE
Miguel evaluates 12 − 2 × 3 and gets 30. Margaret gets 6. Who is right?
- AMargaret, because multiplication comes before subtraction
- BMiguel, because he worked left to right
- CBoth are right
- DNeither is right
✏️ Workspace & Solution Steps
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5 ERROR ANALYSIS
Fix our table's thinking
- 1The problem:Evaluate 4².
- 2A classmate at our table answered:8
Which step contains the error? Explain the mathematical misconception and write the correct calculation below.
✏️ Corrected Mathematical Work & Explanation -
6 ERROR ANALYSIS
Find the error
- 1Expression:Evaluate 20 − 3²
- 2Step 1:3² = 6
- 3Step 2:20 − 6 = 14
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.