In-app purchasing on children's apps.

I'm a mum and an educator, it's too easy to spend money without realising it. 
For tips on how to change your phone settings to avoid costly mistakes see links below. 
How to change settings on Android
http://www.guardian.co.uk/technology/appsblog/gallery/2013/apr/17/how-to-stop-children-inapp-purchases-android?
How to change settings on Apple devices
http://www.guardian.co.uk/technology/appsblog/gallery/2013/apr/17/how-to-stop-children-inapp-purchases-ios?INTCMP=SRCH