Concept mapping has been applied in a variety of fields, including instruction, learning, curriculum development, and assessment. Because many empirical studies have proven the validity of concept mapping, a computer-based concept mapping system has been developed. The system provides two learning environments. In the 'construct-by-self' environment, the system provides students with the evaluation results and corresponding hints for feedback. The students construct concept maps by themselves with only the assistance of the feedback. In the 'construct-on-scaffold' environment, in addition to the feedback, the students receive an incomplete concept map, within which some nodes and links were set as blanks for the scaffold. A study comparing the effectiveness of the 'construct-by-self', 'construct-on-scaffold', and 'construct by paper-and-pencil' concept mapping showed that the 'construct-on-scaffold' had better effect for learning on biology. Both of the two computer-based procedures are helpful for students in completing their concept maps.