In this lesson, students examine the importance of using the domain in a description of a situation where different things are happening. Students encounter situations that encourage them to be precise about interval boundaries and then describe a graph using the domain. In the associated Algebra 1 lesson students look at piecewise functions, including using the function notation to describe the domain of different pieces of a function.

Students must reason abstractly and quantitatively (MP2) when they interpret descriptions of events as piecewise functions. Looking for and making use of structure (MP7) is also essential when defining parts of the domain for which a piece of the function applies.