Paint a picture with your finger. Great for kids 3-5 years old. In fact, I have a hard time getting my iPhone back after lending it to my nephews...
The app starts by displaying a flower bed with 9 flowers. After selecting a flower four colors appear to paint with.
Swipe right to get back to the flower bed and select another flower.
Swipe left to see all the color palettes. Select a palette and swipe right to go back to the flower.
Shaking erases the image.
That's the whole interface. I usually have to show it only once.
This app contains no text or language. This makes it very simple to use for kids.
Once your kids have developed more abilities they will want to select individual colors instead of palettes. You as a parent can then go into the Settings app and set the way in which colors are selected. The three possible ways are: palette, individual colors and the rainbow. In the rainbow mode all the colors slide in and out of the view when you swipe across the colors below the flower.