"I [Paul Hamilton] support some non-speaking children who are learning to use the iPad as a communication device. Sometimes, these learners are inclined to ignore their communication apps because they much prefer other apps. These preferred apps may be worthwhile, but they can get in the way of learning to use the device for its primary purpose. In iOS 6, Apple has introduced an accessibility feature that can help.
Guided Access makes it possible to keep the iPad in a single app, and to control which features of an app are available to a user. In the case above, the iPad might be configured as a dedicated communication device until the user has learned to use it for effective communication. This is only one of many potential situations where Guided Access might be helpful. Of course, Guided Access is also available on the iPhone or iPod Touch."