Here you can find some interesting apps to learn English.
Fun English: Language learning games for kids ages 3-10 to learn, read, speak & spell (2,99 $ per lesson)
Mingoville: The interactive activities encourage children to learn English vocabulary under the “Play-and-learn” mode with intuitive game play and easy menus.
English Basic Concepts : Entertaining and educational application for kids. Basic concepts in English. (Animals, Nature, Home, School, My body, Food, Shapes, colors)