An apple employee pointed out this new feature on the IPad for 'Autistic' kids. It seems really good for young children where you want to limit their control on the iPad. It basically allows certain areas of the iPad to be disabled to touch. link here
P.S. I should warn you before you download the update that you will lose YouTube App as I found out to my own cost. off course you can download replacement YouTube apps but it might not be as familiar to your dc so will have to relearn how to use it.