When Apple releases a new version of their operating systems, they never come with a user’s manual. We (the users) are expected to figure this stuff out as we go. In the case of iOS 6, they boast of over 200 new features, most of which are not specifically spelled out.
One exciting new feature for teachers is something called “Guided Access.” This feature allows you to lock an iPad so that it is “stuck” in one app only. You can do this on-the-fly, and can lock the iPad into any app of your choosing. Once the feature is turned on, it is a simple thing to engage and then turn off when you’re done. For a complete explanation of this feature and how to employ it, check out this post from the OS X Daily blog.