An essential skill for information engineers is learning a new programming language based on ones they have already learned. In this study, a learning method is presented by practicing classes in which students learn Python by comparing it with the C language. Moreover, students are experienced this effectiveness. The students learn C language 6 months earlier. First, C code is presented to review the basics of the C. Next, the same and different points between Python and C language are explained. Then, Python code is presented. This allows students to efficiently learn new knowledge while using their pre-existing knowledge. This method enables them to use Python in a short period. We teach arithmetic, input/output, control statements (conditional branching, repeated statements), collections, and functions in eight classes. In order to evaluate the effectiveness of the method, we have confirmed the questionnaires done on the final class in the 2021 and 2022 academic year. The results are the following. First, more than 80% of the students have found the content appropriate or easy. More than 65% have felt that the learning speed was appropriate, and less than 20% have done that it was fast. More than 72% said that the comparison made it easier to understand contents. These results indicate that the transition of learning based on existing knowledge is realized in the class and that the students is able to experience the benefits of this transition. More than 88% of the students have felt that they understood the differences between C and Python, and more than 67% have done that their knowledge of C was deepened. Several statements about the perceived benefits of the comparison are identified in the feedback. The results of the survey indicate the following. First, this method allows students to experience the benefits of learning from comparison between new programming knowledge and understood one. Secondly, this allows students to learn new knowledge quickly. Finally, many students feel positively about this.