In this lesson, students describe distributions using appropriate terminology. 

• In a symmetric distribution, the mean is equal to the median and there is a vertical line of symmetry in the center of the data display.
• In a skewed distribution, the mean is not usually equal to the median and one side of the distribution has more values farther from the bulk of the data than the other side has.
• A uniform distribution has the data values evenly distributed throughout the range of the data.
• A bimodal distribution has two very common data values seen in a dot plot or histogram as distinct peaks.
• A bell-shaped distribution has a dot plot that takes the form of a bell with most of the data clustered near the center and fewer points farther from the center.

Students practice applying this terminology as they invent reasonable contexts for a described distribution.

The Warm-up activity gives students a reason to begin using language precisely (MP6) and gives the teacher the opportunity to hear how students use terminology and talk about characteristics of the items in comparison to one another. In the Card Sort, as students trade roles, they explain their thinking and they listen to the reasoning of a partner. This provides them with opportunities both to explain their reasoning and to critique the reasoning of others (MP3).