Writing is important because students are through written language to express their ideas to interact with others. However, only few students like writing; on the contrary, most students like scribble. We hope to improve students' interest through scribbling and writing a story on their own or with others. Step by step from scribble to writing, we want to let students feel that they are doing creative works instead of formal writing. Hence, we develop an on-line scribble environment to assist students' writing and to improve their interest of writing, entitled Crazy Brush. We facilitate students to write a story with their produce of scribble. The study process described as follow: firstly, we examined children's the produce of scribble; secondly based on the pilot results, we designed a system which would improve students' interest of writing; finally, we explained how to use Crazy Brush to assist students' writing. Future work will examine the effects of Crazy Brush and further adjustments in the system design.