Smart classroom has some common features such as automatic sensing physical environment,flexible use of computing devices and physical settings,connected learning environment,and learning data tracking.These features can promote interaction among teachers,learning peers and resources entertaining needs of new generation learners.Interactions in smart classrooms have a higher level of complexity in comparison with traditional classrooms.In this study,an interaction observation tool in K-12 smart classroom was developed,based on the existing interaction tools and derived from the characteristics of smart classroom as discussed.The two major parts of the observation tool are interaction records in smart classroom and interaction support from the learning environment.The tool has been piloted in 14 selected primary and secondary schools in Hong Kong,Beijing and Shenzhen.The tool has been revised eight times after thirty times of in-class observation and ten times of video observation.The tool was evaluated in the dimensions of function,usability and data processing by 5 experts of educational technology,10 K-12 teachers and 35 observers.The average mean scores of function,usability and data processing are 4.47,3.98 and 3.94.The Kendall synergistic coefficient is W=0.471,Sig=-0.000,indicating that the tool was highly acceptable.