Startup Idea : Teach a language both reading and writing

An app which helps in teaching a new language. Not just reading but which can teach writing. The screen may be divided into two parts where the top part can show how to write that letter while spelling it out and the user can follow that in the bottom part. It can start with letters then exercises can be designed to write words ans sentences. The app can have several modes for example child or adult mode. child mode can be more descriptive and repetitive and adult' mode can be more quick. If effort's made this app can be extended to as many languages as possible, especially the languages where the script is difficult to write. May be we can give one free course for one language and other courses can be charged.