This applet was derived from Daniel Mentrard's at
http://www.geogebratube.org/material/show/id/21940
A timer was added to make it more challenging.
The applet allows for students to practice the basic skill in expressing the location of a point in the cartesian coordinate system
In this case the student tries to type in the x and y coordinates of the position of the submarine before the time is up.
The timer, ie. the duration of the time for answering can be adjusted.