The purpose of this study is to design a well-guided lessons so that students can not only understand the representation of samples and sampling variability, but also deeply understand and interpret the statistical model of the confidence interval through the project based learning using the exist survey. In the previous research, the representative element of the sample, the sampling variability, the sample distribution, the confidence interval, and the exit survey were extracted and the main learning elements and the predicted learning trajectory were selected by extracting the pedagogical ideas for the guidance. The lessons were designed based on this. In this study, the use of technology can help to understand the variability, and the experience of dealing with the actual data through the exist survey will contribute to the development of the ability to focus on the data and to adequately handle and explain the statistical model, the confidence interval.