1. For each pair of variables, which one makes the most sense as the input? When possible, include a reasonable unit.
   1. the number of popcorn kernels left unpopped as a function of time cooked
   2. the cost of crab legs as a function of the weight of the crab legs
   3.  

      

   4.  

      

   5. , where represents the time that a bike is rented, in hours, and  gives the cost of renting the bike.
   6. , where represents the number of pencils in a box and represents the weight of the box of pencils in grams.
2. Write an equation or draw the graph of a function relating the 2 variables.
   1. Input: side length of a square, output: perimeter of the square
   2. Input: time spent walking (minutes), output: distance walked (meters)
   3. Input: time spent working out (minutes), output: heart rate (beats per minute)

Take turns with your partner to match a function from Column A with its possible inputs from Column B. Be prepared to explain your reasoning for whether or not you include each input.

• For each function, explain to your partner whether or not each input is possible to use in the function.
• For each input, listen carefully to their explanation. If you disagree, discuss your thinking and work to reach an agreement. 

For each function, write 2 additional inputs that make sense to use with these models. Write 1 additional input that does not make sense to use with these models. Be prepared to share your reasoning.