Just to keep them entertained for some time so that I can do my own task :-)

I'm sure there are many apps out there for one year olds, but there are a few in my link that might help you get started. Apps for parents: Best iPad apps for babies and toddlers - iPhone app recommendations - Viki Gonia | Appolicious ™ iPhone and iPad App Directory

Angry birds,

The graphics is good, they don't need to be able to play it.
the colors and shapes should be good of a developing mind.

"Smart Toddler School Pro++" apple app– This all in one or kindergarten prep app provides everything about upper, lower case letters, numbers, colors, shapes, counting and provides good listening and learning. The child will have the opportunity to learn to write, counting, colors, and advanced shapes. My son learns while playing with it for hours and hours.

Rattle apps, the apps for cats were horrendously entertaining. Firstwords UK is really good. It's called Baby Skool. Has a chicken in the app icon. The baby does not have to touch anything. YouTube has Baby Einstein. The videos are about 20 minutes long and keep munchkins entertained.