An interactive applet and associated web page that demonstrate how to find the midpoint of a line segment when the coordinates of the endpoints are given. The applet has two points on a Cartesian plane. As the user drags either point it continuously recalculates the midpoint of the line segment defined by them. The midpoint is shown both on the plane and as a continuously changing formula.

The grid, axis pointers and coordinates can be turned on and off. The midpoint calculation can be turned off to permit class exercises and then turned back on the verify the answers. The applet can be printed as it appears on the screen to make handouts.

The web page has a full description of the method for finding the midpoint, a worked example and has links to other pages relating to coordinate geometry.

Applet can be enlarged to full screen size for use with a classroom projector. After use in the classroom, student can access it again from any web browser at home or in the library with no login required.

This resource is a component of the Math Open Reference Interactive Geometry textbook project at http://www.mathopenref.com.