two lap average [for teachers]

Andrei drives a 60 mile course in 1 hour. How fast does he have to drive a second lap in order to average 120 miles per hour for the two laps? The left panel shows the given data in the {time, distance} plane. The right panel shows the given data in the {time, speed} plane. You can explore the problem by dragging the YELLOW DOT in the left hand panel. - How are speeds represented in the left panel? - How are distances represented in the right panel? - Which representation do you think provides you with more insight? Why? - How can you use this applet to generate more problems of this sort? - What questions could/would you ask your students? - What have you learned about word problems from this applet?