Blind people that are technology literate do not ask this question. Unfortunately, there are a great deal of blind people (sighted too) that are NOT techie and have a difficult time understanding how to use something like an iPad.
All their lives, they have touched something tactile to give them feedback and now they are trying to wrap their mind around using something with a flat surface.
Enter the solution. By hooking a braille display or external keyboard and teaching them the keystrokes, the light bulb of understanding goes on quickly. They begin to see where icons are and how to activate what they want. Then you move them to the Voice Over finger movements and they truly start to understand how to move around this tool and other flat surface tools like it.
Though I have seen this more in adults than children, some children have the same difficultly and once you connect the braille display or external keyboard, (I always teach both), they catch on VERY quickly.
To help your students or if you are blind and are having a difficult time grasping what to do with this flat surface, you can download lessons at: Mac/iTools