A dad shares his list of what good toddler iPhone/iPad apps should do and not do.
Move all settings out of the app. For iOS at least, you can move settings out of the app and into the general settings window. Please do this because toddlers are drawn to your little setting icons, and they a) destroy the flow of the app and b) the toddler will change all of them and put the app into an annoying state, e.g. in another language, too hard for them, etc.