The researchers in education are interested to observing and modeling the learner, and adapting their learning experience accordingly. When learners read and interact actively with their reading materials, they do unselfconscious activities like annotation practices which can be key feature to their personalities. Annotation practices require the reader to be active with the document, to think critically and to make specific annotations in the margins of the text. In this paper we propose modeling learner's personality by referring to their annotations. The experiments show the significant role of annotation activity to reflect certain learner' personality traits.