The mathematical purpose of this lesson is for students to determine whether outliers are present in a data set. In previous grades, students were introduced to the meaning of outliers and calculating the mean. In the associated Algebra 1 lesson, students think more carefully about the outlier to investigate their source and how the presence of outliers impacts measures of center in a context. This lesson prepares students to identify outlier values, investigate their source, and decide whether to remove the values from the data. Understanding outliers’ impact on the mean will help students in fully grasping the impact in a specific context.

Students reason abstractly and quantitatively (MP2) and look for and make use of structure (MP7) when they decide if a data point is an outlier and consider the effects of an outlier. Students look for and express regularity in repeated reasoning (MP8) when using the formula to interpret data. In explaining their answers, students need to be precise in their word choice and use of language (MP6).

Technology isn't required for this lesson, but there are opportunities for students to choose to use appropriate technology to solve problems. We recommend making technology available. Making statistical technology available allows students to choose appropriate tools strategically (MP5) to quickly compute means and improve their problem-solving strategies.