Lesson objective: Understand the best measure of center to represent a data set depends on the type and distribution of the data set.

Students bring prior knowledge of measures of center and variability from 6.SP.3. This prior knowledge is extended to analyzing the measures of center and variance as students choose the best measure of center based on the type and distribution of the data. A conceptual challenge students may encounter is thinking that mean is always the best measure of center.

The concept is developed through work with histograms, which show the different types of distibutions.

This work helps students deepen their understanding of number because they develop the understanding that including all the values when calculating the mean, can cause a skewed mean.

Students engage in Mathematical Practice 2 (reason abstractly and quantitativitely) as they determine which measure of center will best describe the data set. Students can aid their reasoning by creating a dot plot to represent the data sets.

**Key vocabulary:**

- distribution
- interquartile range
- mean
- mean absolute deviation
- median
- mode
- normal distribution
- outlier
- range
- skewed distribution

**Special materials needed:**