Main Window:

The main window contains all the controls needed to use the application. To begin playing, select a function from the Functions box.  The Easy functions are low order polynomials.  The Medium functions are higher order polynomials.  The Hard functions are complex trancendental functions.

Once a function has been selected, click the Start button.  Now begin placing points in the bottom view that correspond to the slope of the function in the top view.  By moving the slider, a line tangent to the function will be displayed.   The values for x and f(x) are displayed in the text fields in the upper right of the window.  By typing text directly into the x position text field, the x position (and thus the slider) may be set exactly.  

If a point is placed in the wrong position, click the Undo button to remove it.  By recursively clicking the Undo button, all points may be removed.  

A maximum of ten points may be placed in the bottom view.  Once satisfied with the placement of the points, click the Stop button.  This will display the actual derivative curve in the same view with the estimated points.  Additionally, a score will calculated based upon the accuracy of the points.  A score of 100 is perfect (and practically unachievable.)  A score in the nineties is a good score.  
 
The game need not be played to use this application.  Simply click the Start button then cick the Stop button to reveal the dervative curve immediately.  Then use the slider to carefully study the relationship between the function and its derivative.  The the slope (f'(x)) will be displayed along with x and f(x) in the text fields in the upper right of the window.