I will give my ICS tablets for users to complete a survey so I would like the user to work with my app only. They should not be able to switch to the home screen, press back
To complement the answers already given, and in case it is useful for someone needing a similar behaviour, there is this tutorial for android devices 4.0 and higher, it tells you how to hide the navigation bar and the status bar (they will reappear when the screen is touched again):
https://developer.android.com/training/system-ui/navigation.html
I realize it is not what you need exactly, but might be useful for someone else looking at this problem.