Relating Tangent values to the derivative function

Drag A on f(x) to see the graph of the derivative by seeing the relationship between the tangent value and the derivative value at a point.
Drag A along f(x)[br]Are there any places that the derivative is not continuous?[br]Pick a different function for f(x) (a suggestion--move A back to x=0 before starting so that you can find A!)

Information: Relating Tangent values to the derivative function