The mathematical purpose of this lesson is for students to understand the importance of randomness in selecting a sample and in assigning participants to groups for an experimental study. Students encounter the term random selection, which is used to describe a selection process by which each item in a set has an equal probability of being selected. They are also reminded of the term “sample,” which is defined as a group that is selected from the whole population. When students describe the importance of randomness in selecting samples and dividing groups in the context of a study, they are attending to precision (MP6).