Student modeling approaches predominantly focus on modeling student knowledge. For effective learning, however, it is necessary to teach students how to learn, as well as to provide support for learning domain knowledge. Recently, a number of projects focused on students’ learning strategies, and initiated work on modeling students’ metacognitive skills, such as self-explanation and reflection. This paper focuses on self-assessment as an important metacognitive skill. We present results of an initial study carried out in the context of SQL-Tutor, a system that helps students to learn a database language. We found that not all students are good at evaluating their own knowledge, and that their knowledge level is an important factor. The study is an initial step towards incorporating the meta-level into the existing student model in SQL-Tutor.