Deriv Explorer 2
This applet allows you to explore the relationship between f(x), f'(x), and f''(x). You can show the original function, the first derivative, and the second derivative by clicking the appropriate checkbox. You can show any one, two at a time or all three. Change functions by sliding the Function slider. By clicking the trace button, you can see the tangent line at a point on the function determined by the position of point A.