We finished our 4 representations of iCost lesson (started Thurs). It was hard to capture all the discussion going on with students and their ideas of figuring out slope. Ideas were quite rough among most students BUT got smoothed out after students justified their thinking, referring to our definition of slope and y-intercept. It was very hard for them to think of a situation that included iPads. They wanted to always be increasing money. Which gives me a clue into having to vary the situations I give them next time.