Teaching informatics allows students to work out solutions for given problems. If this is done with typical elements in an object-oriented manner, they will find out objects and discuss several possible ways to structure a solution by combining the work of these objects. After this there is a sequence in which objects interact to solve the given problem. Last but not least students have to test their solutions and discuss them. Implementing at sourcecode level is essential to acquiring basic insights and to help students to find out that "code rules". Nowadays students grow up in an environment, where they use mobile phones and not desktop computers in everyday life. Mobile phones allow students to code wherever they are and at whatever time they wish. They may spend time on programming, testing and modifying their solutions without paying any fees. To provide proof of this concept, a regular course at secondary II level - K11-grade - with 29 students (19 female and 10 male) was given the opportunity to work with mobile phones alone, without access to desktop computers.