In this study, the answers to the questions; "What are the misconceptions primary school students have in Colors issue in Optics unit in Science & Technology course" and "How to remove them?" have been sought. The aim of the study is to detect student misconception related to the concept of 'color' and to correct them by applying a Computer Assisted Instruction (CAI) material. POE (Prediction-Observation-Explanation) technique was chosen as detecting and removing means of misconceptions. In the study a CAI material, which is suitable for the application of observation steps of POE technique, was developed and worksheets were prepared for Prediction and Observation steps.