While it might be easier to simply disable the App Store for a two-year-old or a four-year-old, it may be easier to allow your pre-teen greater access to the i Pad.This is where the age-based restrictions come into play.
In-app purchases have essentially taken over the economic model oft the app store.
You can turn off In-App Purchases within the same screen as the other restrictions.
The setting is towards the bottom of Allowed Content, right above the time interval for requiring a password.
When you turn off in-app purchases, the option to buy these extras within games and apps will be disabled.
This means no surprises when the i Tunes bill comes in your email.
By default, the App Store will prompt for a password for even a free game or app, but if you have recently typed in your password, there is a grace period where apps can be downloaded without being verified.