The Open University

To date there has been very little work on the machine understanding of imprecise diagrams - diagrams drawn by students in response to assessment questions. While there have successful attempts at assessing text (essays) automatically, little success with diagrams has been reported. In this paper, we explain an approach to the automatic interpretation of graph-based diagrams based on a 5-stage framework. The paper reports on the evaluation of some experiments in automatically grading student diagrams produced under examination conditions which show good agreement with the performance of human markers. The paper also describes how the automatic marking algorithm is being used in a variety of teaching and learning tools.