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.
- 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.
Let’s explore ways to get representative samples.
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.
The demonstration will also require a ruler marked with inches to measure the straw pieces chosen in a sample.
- 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.
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