Lesson
Plan Title:  Same Origin Policy Protection. 
Concept /
Topic To Teach: 
A key element of AJAX is the XMLHttpRequest (XHR), which allows javascript to make asynchronous calls from the client side to a server. However, as a security measure these requests may only be made to the server from which the client page originated. 
General
Goal(s): 
This exercise demonstrates the Same Origin Policy Protection. XHR requests can only be passed back to the originating server. Attempts to pass data to a non-originating server will fail.
Solution: 
Click both of the links on the page to see their behavior and complete the lesson.