The chapter adopts the framework of Technological Pedagogical Content Knowledge (TPCK) in order to redesign the teaching of three computer science lessons about (a) three basic computer science concepts, namely, data, processing, and information, (b) the representation of data in computer language, and (c) the differences between main and secondary memory. The chapter uses the systematic guidelines of technology mapping to transform the teaching content with the use of educational technologies and in particular spreadsheets. While the framework of TPCK and the guidelines of technology mapping proved to be adequate methodological frameworks for the teaching of computer science, it is pointed out that the focus herein has been on the cognitive domain of learning, and that the frameworks have to be also tried out within the context of other subject-matter areas where the emphasis is also on the affective domain of learning.