Go SPEED Racer: Exploring Speed

Last year I wrote a post called Go Speed Racer... it's all about engaging students when beginning a unit on graphing and calculating speed.    Okay, so you have their attention, but how on earth can you really explore speed...from the fast to the slow or even better... stopped.  How is that graphed?  As I did the engage and watched my students hypothesize about the hare's...