Khattapan, C. N. THE CASE STUDY RESEARCH OF EXAMINING THE USEFULNESS AND PERCEPTION OF THE ONLINE TEACHING PREPARATION PROGRAM: Received: 13th November 2021; Revised: 17th May 2022, 21st May 2022, 24th May 2022; Accepted: 24th May 2022. pijtel 2022, 6, 359-372.