One plate is considered moving while the other is considered fixed. Students may then draw a vector on a map showing the direction and speed of the moving plate. The velocity and direction of the moving plate will provide the information needed by the student to mark their maps. The latitude and longitude entered confirms the given location. Note that the direction of each plates relative movement is the complement of the other, and the velocity is identical.
Scientists use vectors to represent plate motion on maps.
A vector used in this situation is an arrow pointing in the direction of plate motion with a length proportional to the plate speed. Getting the arrow correct involves constructing an angle and a length. Since plates move a few centimeters per year, it is natural to make the arrow the same length as the plate movement. In the case of the absolute plate motion at Chicago, the arrow should be 2.55 cm in length. Because direction is given in degrees, a protractor is used to construct the angle corresponding to the plate's direction of movement.