The Two Body Orbits model for teachers shows the motion of two objects (binary star or moon-planet system) interacting via Newton's law of universal gravitation.  It is designed to teach physics, Earth science, and environmental science topics by showing the spatial path of objects around their common center of mass (barycenter).  An optional 3D view shows the celestial sphere and and the orbital plane (ecliptic).  Default units are chosen for Earth obit about our Sun so that the distance unit is one astronomical unit and the time unit is one year.
 
An important feature of the ready-to-run Two Body Orbits simulation is that it can be customized by teachers to meet various learning objectives. The teacher sets the ratio of the two masses, their initial positions and velocities, and various visualization and scale parameters.  Documentation, such as an exercise or lesson, can be added to the simulation by entering a filename into the Customization dialog.  Selecting the "student" checkbox creates a ready-to-run package with the new configuration without the Customization dialog.

The Two Body Orbits model was created using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run Java archive.  Double clicking the ejs_mech_orbits_TwoBodyOrbits.jar file will run the program if Java is installed.  EJS is a part of the Open Source Physics Project and is available in the OSP Collection.

Please note that this resource requires at least version 1.6 of Java.