Research on the development of computer-assisted instruction on the principles of computer system work For 80th grade students in Poochareon Witthayakhom School, 2nd semester of the academic year 2019, with the objective of 1) to develop and find the efficiency of computer-assisted instruction on working principles of computer systems For mathayomsuksa 2 students 2) to compare the learning achievement on the computer system work of mathayom suksa two students learning by using computer assisted instruction. With the group learning through the normal methods The data was analyzed by means of means, standard deviation. Performance evaluation (E1 / E2) and t-test Research instruments 1) Computer assisted instruction lesson 2) Learning achievement test

The results of the research revealed that 1) Computer Assisted Instruction Lesson on Working Principles of Computer Systems. For Mattayomsuksa 2 students, they are in very good quality. With an average of 4.97, a standard deviation of 0.18 and an efficiency of 87.50 / 87.86. 2) The learning achievement of mathayom suksa two students learning through computer assisted instruction had an average value of 8.95, higher than the group learning by method. Normally had an average 7.87 level of statistical significance at the level of .05