As a part of language learning at schools and universities, students write a variety of texts, such as essays, short compositions and reports, which are then read by teachers who typically comment on the content and grammar of these texts to help the students improve their skills as writers. Although teachers can simply use pen and paper, or a text processor, to provide written feedback, the traditional annotation methods do not usually allow easy and systematic re-use of self-explanatory comments for helping the students to revise their writing. For these reasons, we have developed a new online-based commenting/annotation tool, KungFu Writing, which was designed for giving more elaborate feedback on written assignments. As the system is accessible online through a web browser, the tool also allows new opportunities for teachers to collaborate in teaching writing skills at all levels of education. This paper describes the main features and typical uses of this new feedback tool. [For the complete volume, see ED574893.]