Mission 7 · Unit 3
Percent Reasoning
6.RP.A.3.C · Unit 3Need a hint?
The sixth-grade student council is planning a school supplies drive. They surveyed 250 students about which supplies they need most. The results show that 35% need notebooks, 22% need pencils, 18% need folders, 15% need erasers, and 10% need glue sticks. Your team must convert every percentage to a fraction and a decimal, calculate the exact number of students in each category, verify the total, and recommend how to split a $500 donation budget across the five supply categories proportionally.
Team Roles
Investigation
The Problem
A survey of 250 sixth graders found that students need five types of school supplies. The results are expressed as percents:
- Notebooks: 35%
- Pencils: 22%
- Folders: 18%
- Erasers: 15%
- Glue Sticks: 10%
Your tasks:
- Convert each percent to a fraction (simplify!) and a decimal.
- Calculate the exact number of students for each category.
- Verify that the five student counts add up to 250.
- Split a $500 donation budget proportionally based on the survey percentages.
- Create a visual model (bar model, pie chart, or number line) that shows how the five categories compare.
Step-by-Step Investigation Guide
-
Verify the percents add to 100%
Before converting anything, add: 35 + 22 + 18 + 15 + 10. If the
sum is not 100%, something is wrong with the data.
Why must survey percents always add to exactly 100%?
-
Convert each percent to a fraction
Write the percent over 100, then simplify. Example: 35% = 35/100
= 7/20. Find the GCF of the numerator and 100 to simplify.
Which of the five percents produces the simplest fraction? Which is hardest to simplify?
-
Convert each fraction to a decimal
Divide the numerator by the denominator. Example: 7 / 20 = 0.35.
Check: does the decimal make sense compared to the percent?
How can you check your decimal without a calculator? (Hint: think about equivalent fractions with denominator 10 or 100.)
-
Calculate the number of students per category
Multiply each decimal by 250. Example: 0.35 x 250 = 87.5. Wait
-- can you have half a student? Discuss how to handle non-whole
results.
If 0.35 x 250 = 87.5, does the survey data make perfect sense for exactly 250 students? What does this tell you about rounding in surveys?
-
Calculate the budget allocation
Apply each percent to $500. Example: 35% of $500 = 0.35 x 500 =
$175. Check that all five amounts add to exactly $500.
Why is it important that the budget allocations add to exactly $500? What happens if they do not?
-
Build a visual model and prepare your defense
Create a bar model, pie chart, or stacked number line that shows
all five categories with fraction, decimal, AND percent labels.
Write a one-sentence recommendation for how to spend the $500.
Which visual model makes it easiest for another student to compare the five categories at a glance?
Percent Calculator Tool
Enter a percent and a total to find the part. Use this to check your work.
Visual Bar Model
To simplify a fraction, find the GCF of the numerator and the denominator, then divide both by it.
- 35/100: GCF of 35 and 100 is 5, so 35/100 = 7/20
- 22/100: GCF of 22 and 100 is 2, so 22/100 = 11/50
- 18/100: GCF of 18 and 100 is 2, so 18/100 = 9/50
- 15/100: GCF of 15 and 100 is 5, so 15/100 = 3/20
- 10/100: GCF of 10 and 100 is 10, so 10/100 = 1/10
Multiply each decimal by $500:
- Notebooks: 0.35 x $500 = $175
- Pencils: 0.22 x $500 = $110
- Folders: 0.18 x $500 = $90
- Erasers: 0.15 x $500 = $75
- Glue Sticks: 0.10 x $500 = $50
Check: $175 + $110 + $90 + $75 + $50 = $500
Language Support
Key Vocabulary
Sentence Frames
- "___% means ___ out of every 100, which equals the fraction ___."
- "To convert ___% to a decimal, I divide by 100 and get ___."
- "___% of 250 students is ___ students because ___ x 250 = ___."
- "The budget for ___ should be $___ because it is ___% of $500."
Multiple Representations
Conversion Table
Organize all five items in rows with columns for percent, fraction, decimal, students, and budget.
Bar / Strip Model
One long bar = 100%. Divide it into sections proportional to each category.
Pie / Circle Graph
Divide a circle into five sectors. Label each with all three forms.
Double Number Line
Top line shows percents 0-100. Bottom line shows student counts 0-250.
Work Space
Conversion Table:
| Supply | Percent | Fraction | Decimal | Students | Budget |
|---|---|---|---|---|---|
| Notebooks | 35% | ||||
| Pencils | 22% | ||||
| Folders | 18% | ||||
| Erasers | 15% | ||||
| Glue Sticks | 10% |
Total students check: ___ + ___ + ___ + ___ + ___ = ___
Total budget check: $___ + $___ + $___ + $___ + $___ = $___
Visual Model:
Recommendation and Defense: