Physics (13). This project is creating and testing an online system named Teamworks for collaborative laboratory report writing. Individual students in a lab team make additions or changes to the report through a web browser, either in the lab or remotely, and the team decides collectively whether to accept each student's change or ask for it to be rewritten. The students in the team also decide collectively when the report is finished. Detailed information about the writing process is stored in the system and is reported to the instructor for use in grading or doing educational research. Teamworks is designed for writing undergraduate lab reports. It includes graphing and drawing tools and an equation editor. It is used by individual students as well as collaborative groups. Intellectual Merit: The project is creating a system designed to encourage students to make individual contributions to collaborative written reports, and to read and comment on their teammates' contributions during the process. It gives instructors data that will help them grade reports. Broader Impact: The system will be available to instructors at all institutions who teach introductory and advanced labs in physics. It will also be suitable for use in other science and technology disciplines, and in distance learning and blended learning. It is being designed not only as a teaching tool but also as a tool for educational research on writing in science learning that will inform our knowledge of student cognitive approaches to writing.