# Interpreting function notation in context

## Interpret statements that use function notation in terms of the quantities represented (F-IF.A.2).

In this section, students apply and extend their understanding of function notation in various contexts by interpreting statements that use function notation in terms of the quantities represented.

1 Cell phones

WHAT: This task asks students to interpret four statements about a function $f$, where $f(t)$ is the number of people, in millions, who own cell phones $t$ years after 1990. The four parts of the task progress in abstraction from $f(10) = 100.3$ to $n = f(t).$

WHY: This task is an opportunity for students to explain, in their own words, how they understand statements that use function notation and variables that represent quantities in different units (MP2).

2 Yam in the Oven

WHAT: This task asks students to explain in everyday language four statements that involve a function $f$, where $f(t)$ is the temperature of the yam $t$ minutes after itâ€™s placed in the oven: $f(0) = 65$; $f(5) < f(10)$; $f(40) = f(45)$; $f(45) > f(60).$

WHY: This task is an opportunity for students to explain, in their own words, meanings of statements given in function notation (MP2). Unlike the previous task (Cell Phones) and the tasks in section 2, this task asks students to interpret inequalities and equations about pairs of values of the function.