The purpose of this activity is for students to start thinking about what they need to know when facing problems with unusual units of measurement. Students are faced with the situation that a person is running a marathon and, from the picture, can see that the person is currently on mile 6. Students will approach this situation with different knowledge about and experience with marathons, which will impact the questions they craft.

The goal of this discussion is for students to consider more mathematical questions about the situation. Invite several partners to share one question with the class, and record responses. Ask the class to make comparisons among the shared questions and their own. Ask, “What do these questions have in common? How are they different?” Listen for and amplify language related to the learning goal, such as adding context to the situation. Since students will see a similar prompt in a future estimation Warm-up, focus the discussion on questions students can ask to gain the information they need to interpret the context.

The goal of this activity is for students to learn how to calculate standard deviation ( or ) using technology. Standard deviation is a measure of variability. The work in this activity prepares students to be successful in a future Algebra 1 lesson when they have to calculate the standard deviation of data sets. 

The goal of this activity is for students to practice the skill of comparing data sets by comparing standard deviations. Previously, students discovered the importance of variability in comparing data sets when they chose the better choice first, then calculated the standard deviation and reflected on whether or not variability was a factor in their decisions. This activity gives students the opportunity to calculate the standard deviation and use it to inform their decisions first. Students reason abstractly and quantitatively (MP2) when they use appropriate statistics for a situation to decide a better option.