Student Worksheet — Session 3: Sampling Strategies

Data Science for Young Minds · Grade 5 · Ages 10–11

Name

Date

Partner Name

Part 1 — Vocabulary

Population

Sample

Random Sample

Convenience Sample

Representative

Sample Size

Part 2 — Bead Jar Simulation Data

True distribution (revealed at debrief): Red: 40% · Blue: 30% · Yellow: 20% · Green: 10%

Bar Graph: Compare your 10-bead and 30-bead results to the true distribution (use two different colors).

Y-axis = Percentage (0–100%). Color key: _____ = 10-bead draw _____ = 30-bead draw _____ = True %

Red

Blue

Yellow

Green

Draw bars for each color using both sample sizes and the true %. Label your bars.

Part 3 — Sampling Method Identification

Identify the sampling method used in each scenario. Write: Random / Convenience / Stratified

Scenario	Method	Why might this cause bias?
A researcher surveys the first 50 people who walk into a shopping mall.
Names of all 500 students are put in a hat; 50 names are drawn.
A school surveys 5 students from each of its 10 grade levels.
A researcher only asks their friends and family for the survey.

Part 4 — Analysis Writing

Which sample size gave you a more accurate picture of the jar — 10 beads or 30? Use your actual data (percentages) to explain your answer.

Predict: What would happen to your results if you drew 50 beads? 90 beads? Explain your reasoning.

Could a 10-bead sample ever give a perfect result? Would that mean 10 beads is always good enough? Explain.

Part 5 — Percentage Practice

Formula: count ÷ sample size × 100 = %

1. You drew 30 beads: 14 red, 9 blue, 5 yellow, 2 green. Calculate the % for each color:

Red: ____% Blue: ____% Yellow: ____% Green: ____%

2. The true distribution is 40% red. How far off was your red result? _____percentage points

3. If you surveyed 200 students from a school of 2,000, what percentage of the population did you sample? _____%

4. Is 10% a good sample size? What else would you need to know to answer that question?

Take-Home Challenge — Spot the Sample

Find one news article, advertisement, or statistic that uses a survey or study. Analyze the sampling.

Source/headline: ___________________________________________

How many people were sampled? _______ Out of a population of approximately: _______

What sampling method do you think they used? How do you know?

Is this a representative sample? What might be missing?

My conclusion about whether this sample should be trusted: