Lesson objective: Understand that the arithmetic mean is a balance point of all the data.

Students bring prior knowledge of bar graphs from 4.MD.B.4. This prior knowledge is extended to calculating measures of central tendency as students use a bar graph to find the mean. A conceptual challenge students may encounter is understanding the mean as an equal reallocation of the data.

The concept is developed through work with bar graphs, which allows students to manipulate the bars and understand the mean as a redistribution of data.

This work helps students deepen their understanding of number because the center of a dataset can be described using a single number.

Students engage in Mathematical Practice 4 (Model with mathematics) as they manipulate a bar graph to represent the mean as an equal redistribution of data.

**Key vocabulary:**