Teaching kids how to create and design apps.

I would like to teach the children in my class (9 to 11 year olds) how to design and create simple apps for iOS, are there any ready made lessons/ resources/ platforms or help out there?

We have a set of iPad 2's and we are looking to teach more computer science in school but I am having trouble finding help out there as it's quite a new area we are looking into. With the younger kids it's difficult to find things that are accessible for them; I don't want to limit them in what they can do because they are young. I am planning for them to take a load of electrical things apart in the next few weeks to get some knowledge of actual circuit boards within items - we have investigated and learnt about elecricity in our science lessons and I want to challenge and inspire them.

Is there any help out there for this?