This paper describes research on the perception of undergraduate students of the concept of reduction. Specifically, based on an analysis of students' answers to questions addressing different CS topics, we present several findings regarding the ways in which undergraduate students conceive of and apply reduction. In addition to the research description and results, the paper discusses the role of reduction in CS and suggests several teaching applications. Categories and Subject Descriptors K.3.2 [Computers and Education]: Computer and Information Science Education – Computer Science Education. General Terms Theory. Keywords Reduction, Reductive Thinking, Computational Models, algorithms.