This study explores the effect of user and system characteristics on our proposed web-based classroom response
system (CRS) by a longitudinal design. The results of research are expected to understand the important factors
of user and system characteristics in the web-based CRS. The proposed system can supply interactive teaching
contents, quizzes, and questions from its database. In addition, the system provides three playful classroom
response modes--the individual assigned mode, the rush answering mode, and the pushing button mode--to
increase computer playfulness, friendly interface, and interactivity for students. Both user and system
characteristics are based on the external variables from the technology acceptance model (TAM). The results of
the longitudinal empirical study indicate that the effect of user characteristic on perceived usefulness is more
than that of system characteristic, while the effect of system characteristic on perceived ease of use is more than
that of user characteristic. Furthermore, the difference between short-term use and long-term use is analyzed. In
the user characteristic, the effect of long-term use on perceived usefulness is more significant than that of
short-term use. The effect of system characteristic on perceived usefulness is insignificant for long-term use, but
that is significant for short-term use. The effect of long-term use on perceived ease of use is more significant
than that of short-term use. In addition, computer playfulness is positively related to perceived ease of use, while
subjective norm affects directly on perceived usefulness