4.5 Small Group · Group 1
Tier 2 Intervention · Concrete-Representational-Abstract (CRA) · Dual-Language Anchors
Determine the Whole Given the Part and Percent · Part · Procedural Fluency · Reasoning & Critique
- When you know a part and the percent it represents, the whole is what is missing. A double number line, a ratio table, or an equation will each get you there — the equation is the fastest once you trust it. We'll walk through a worked example, try one together, then you'll try a few with hints right there when you need them.
- Akela paid $42 for a sweater on sale, and that was 60% of the original price. The $42 is the part; the original price is the whole, which is 100%.
- On a double number line, I put $42 under 60%. To find a smaller step, I use 10%: if 60% is $42, then 10% is 42 ÷ 6 = $7.
- Now I count up to the whole: 100% is ten of those 10% steps, so 10 × $7 = $70.
- The equation says the same thing in one move: 0.6 × v = 42, so v = 42 ÷ 0.6 = 70. The original price was $70 — larger than the sale price, which is exactly what a discount should mean.
- Determine the Whole Given the Part and Percent (Hallar el total dados la parte y el porcentaje) — Working backwards from a part and its percent to find the whole amount it came from.
- Part (Parte) — The amount you already know — the piece of the whole that the percent describes.
- Whole (Total) — The full amount the percent is measured against. The whole is always 100%.
- Double number line (Recta numérica doble) — Two lines lined up — dollars on one, percents on the other — so matching marks show the same amount two ways.
- Equation (Ecuación) — A math sentence with an equal sign. Here it says percent × whole = part, with the whole unknown.
- Percent (Porcentaje) — A ratio comparing a number to 100. To compute with it, write it in decimal form: 60% = 0.6.
- A common mistake when finding the whole is multiplying by the percent instead of dividing. For "$42 is 60% of the original price," computing 0.6 × 42 = $25.20 makes the original price SMALLER than the sale price — impossible for a discount. Since percent × whole = part, the whole is found by dividing: 42 ÷ 0.6 = $70. Whenever the percent is less than 100%, the whole must come out larger than the part, so a smaller answer is the tell.
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1 DRAG SORT
Sort each number by the role it plays in "$42 is 60% of the original price."
- $42
- 60%
- the original price
- the amount Akela paid
- 0.6
- 100%
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2 FILL TABLE
$42 is 60% of the original price. Complete the ratio table to reach 100%.
Percent Dollars 60% 10% 100% ✏️ Scratchpad / Reasoning
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3 MULTIPLE CHOICE
$20 is 50% of what number?
- A$40
- B$10
- C$25
- D$70
Work- 1Whole100% is what number?
- 2Find 10%Divide by 10.
- 3BuildAdd or multiply to the percent.
- 4CheckIs it under or over the whole?
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4 MULTIPLE CHOICE
Which equation says "30 is 25% of some number n"?
- A0.25n = 30
- B25n = 30
- Cn = 0.25 × 30
- Dn = 30 + 25
✏️ Workspace & Solution Steps -
5 MULTIPLE CHOICE
$42 is 60% of the original price. Should the original price be more or less than $42?
- AMore, because 60% is less than the whole
- BLess, because 60 is a big number
- CExactly $42
- DYou cannot tell
✏️ Workspace & Solution Steps -
6 MULTIPLE CHOICE
75 minutes is 15% of the school day. How long is the school day?
- A500 minutes
- B11.25 minutes
- C90 minutes
- D1,125 minutes
Work- 1Whole100% is what number?
- 2Find 10%Divide by 10.
- 3BuildAdd or multiply to the percent.
- 4CheckIs it under or over the whole?
Group Discussion Prompt: How does your visual model justify your mathematical solution?
Partner A: "I modeled this by identifying the relationship and..."
Partner B: "I agree with your step because the standard mathematical rule states..."
Complete each sentence stem to demonstrate precise mathematical reasoning:
Writing Task: Justify why your mathematical solution is accurate and complete.