Instructional supervision should be based on accurate class observation. For class observation and analysis, observation training is essential to properly use class observation tools verified by research. Class observation training in the MET study in U.S. is conducted systematically for an average of 17 to 25 hours, focusing on the accurate use of class observation tools. Class observation programs in Korea s head teacher qualification training course consist of about 10 percent(10 hrs) of the total(102 hrs), and in-service job training programs after appointment as head teacher consist of about 6%(5 hrs.) of the total(79 hrs). Compared to the MET, Korea has a relatively low ratio in reference to class observation. Comparing the respective consistency of the first and second class observation practices in the class observation training using ICALT, a quantitative observation tool, in Korea, the consistency of the second class observation increased by 14.9% compared to that of the first class observation. As class observation and analysis training were repeated, class observation expertise was improved. To cultivate professional class observers, there is a need to train a class observation specialist focused on systematic observation on teaching and coaching using scientific tools to ensure the continued reliability of the results of class observation, and follow-up studies are needed on how to produce master class videos and coach classes using ICALT tools to help understand the tools.