Using Guided Access
Guided Access is a great new feature of iOS 6 that lets you restrict what someone can do with your iPad, iPhone, or iPod Touch. This feature works especially well for an app like Pretty Numbers that's designed for small children, who may unintentionally press the home button or use gestures to leave the app.
To use Guided Access to keep a particular application running:
1. Enable Guided Access
In your device's Settings, tap General, and then Accessibility. You should find an item entitled "Guided Access". Tap on it, and turn it on. (If you don't see the Guided Access setting, make sure you're running at least iOS 6).
When you turn on Guided Access, you have the option to enter a passcode now, or you can do it later. You can also decide whether the device should go to sleep normally, or be forced to stay awake while in Guided Access.
You only need to complete this step once.
2. Start the App
Launch the application you want to keep in the foreground.
3. Start Guided Access
Now that the app is running, tap the Home button three times quickly. Guided Access will appear. Press the Start button.
If you haven't already configured a passcode, you'll be asked to do so now. If you're using Guided Access simply to prevent your child from accidentally exiting the application, then a secure passcode isn't important here. I'd suggest using something easy to remember, like 0000.
Now that you're in Guided Access, how do you get out? Again, tap the Home button three times quickly. You'll be asked to enter the passcode again, and then you can press Cancel to end Guided Access.