The Guided Access offers you the possibility to run an iOS App permanently in the foreground. By activating you can protect the opened app against undesired user interactions and deactivate e.g. hardware buttons. The guided mode can be exited by entering a code or the settings can be changed.
Guided access can be achieved as follows:
Settings -> Accessibility -> Guided Access
Notice: You should prefer a wall mount that covers all existing buttons. In Guided Access Mode every user can try to unlock the device with a wrong PIN. The device will be blocked longer and longer for every erroneous tryout. Here you find some iPad wall mounts