Having now familiarized students with the y=mx+b form and reminding the students to think covariationaly, Ms. Coombs introduces a problem to serve as a point of ongoing discussion to develop another form for linear functions – one that allows for finding an equation when given a point and a rate of change. 

Ms. Coombs continues with the discussion, but she also includes the information that she was traveling at ½ mile per minute.