# Lesson 10

Sampling in a Fair Way

### Lesson Narrative

In this lesson, students consider different methods of selecting a sample. Students begin by critiquing different sampling methods for their benefits and drawbacks. In particular, students notice that some sampling methods are more biased than others. A follow-up activity shows that some methods may seem to be unbiased at first, but have a hidden bias that restricts the sample from being representative of the population. Finally, students practice recognizing when a sampling method is likely to be biased (MP3), and they see that selecting a sample at random is more likely to produce a representative sample.

### Learning Goals

Teacher Facing

• Describe (orally and in writing) methods to obtain a random sample from a population.
• Justify (orally) whether a given sampling method is fair.
• Recognize that random sampling tends to produce representative samples and support valid inferences.

### Student Facing

Let’s explore ways to get representative samples.

### Required Preparation

For the That’s the First Straw activity, prepare one paper bag containing straws cut to the specified lengths in the table for a demonstration.

 $$\frac{1}{2}$$ 1 2 3 4 5 6 6 8 6 5 4

The demonstration will also require a ruler marked with inches to measure the straw pieces chosen in a sample.

### Student Facing

• I can describe ways to get a random sample from a population.
• I know that selecting a sample at random is usually a good way to get a representative sample.