Derivative Intuition

This nice idea for developing intuition fro the derivative as slope or instantaneous rate of change came from a student's program on the Khan CodeAcademy, via Sue Van Hattum. I may have seen something similar from Marc Renault or Mike May. Use the red points to match the red tangents to the slope of the function. Use the green free point to try to trace the slope. (MUCH harder.)
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