The sampling method used in this scenario is systematic sampling.

In systematic sampling, a researcher selects every nth item or individual from a larger population. In this case, the P.E. coach selects every third student from the line of all students in the class.

Characteristics of Systematic Sampling:

1. The population is organized in some order (e.g., a line).
2. A fixed interval (every third student) is used to make selections.
3. The method ensures representation across the population as long as the list isn’t ordered in a way that could introduce bias.

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Would you like more details or have any questions?

5 Questions to Expand Understanding:

1. How does systematic sampling differ from random sampling?
2. Could the order of students in the line affect the validity of the sample?
3. What are the advantages and disadvantages of using systematic sampling?
4. How can bias be introduced into a systematic sampling process?
5. In what situations would systematic sampling be most useful?

Tip: Always ensure that the interval chosen in systematic sampling doesn't inadvertently introduce patterns or biases related