Reflective learning refers to a learner's purposeful and conscious manipulation of ideas toward meaningful learning. Blogs have been used to support reflective thinking, but the commonly seen blog software usually does not provide overt mechanisms for students' high-level reflections. A new tool was designed to support the reflective thinking process. Beyond writing blog posts, the tool allowed users to attach up to five keywords to each post and link the keywords on a concept map. This study aimed to seek evidence of reflective thinking in participants' keyword-attaching activities. Data analysis included producing mental maps of the blog texts, calculating nodes of high centrality (most talked-about nodes and most connected nodes) with the help of software including AutoMap and Organizational Risk Analyzer, and comparing student-generated keywords against mental map nodes. Results of keyword analyses revealed that two-thirds of the student-attached keywords matched mental map nodes. Results also indicate that the map analysis method can produce reliable indexes of a given text, which in turn could serve as anchor points for further content analysis. Other findings also uncovered some differences between participant-selected keywords and mental map nodes, indicating different levels of reflective activities.