This paper describes the use of the concept of an Open Learner Model as a means by which students can be supported in their reflection on their learning at University level. The work is situated within a ―blended‖ learning environment consisting of both classroom teaching and an online learning management system (Moodle). The topic studied by the students is a second year module on ―Computer System and Architecture‖. This work focuses on how blended learning has an impact on learning achievement comparing to the normal classroom learning with the same learning contents. The results show that students from blended learning environment have a bigger difference in mean scores comparing between pre-test and post-test. Furthermore, the significant correlations between AllTest, NetScore and Post-test can be inferred that this way of learning, through responsibility and self-regulation - the way of knowing themselves - for lesson activities of learners is a key factor for successful learning.