Abstract
Comparing online and paper-based environment for report submission and correction, the former supersedes to the latter, since (1) the turn-around time becomes shorter, (2) teaching opportunity increases, and (3) as a consequence, the student's achievement level becomes higher in the online environment. In this paper, we propose an annotation tool GABA for PDF document in order to reduce correction time by the teachers and to facilitate instruction to students. In a usual class, the same or similar assignments are given to the students. Then it is often the case that many students make similar mistakes. A teacher can register and classify common correction comments to GABA. Report correction time becomes significantly shorter by reusing the registered comments. GABA also provides various support functions in order to assist efficient checking of numerous report files such as (1) sorting of frequently-used comments, (2) similarity-based file sorting, and (3) cross tabulation of comments using category and weight.