Firstly, it explains the necessity and even urgency of setting up calligraphy class, and then it talks about what it brings to students and schools. Finally, talk about the possibility of adding new classes from your current academic status: for example, is there such a teacher in the school? Do students have such energy and interest? Is it a self-study class or a class reduction? ...
In fact, many schools now offer calligraphy classes. Your idea is very good. First of all, it is good for children. Put forward your ideas bravely. At least, the headmaster will appreciate your idea and hope to help you!