Since the introduction of CAS (Computer Algebra Systems), educators are experimenting new ways of teaching with the aim to enhance many aspects of the learning mathematics. In particular, visualization can aid the understanding of concepts. The graphical potentialities of many CAS, in fact, allow students to discover concepts, relationships, rules, so as to construct their knowledge for themselves. The aim of this work is to present a Mathematica notebook that enables students to use visualization skills to better grasp the mathematical concepts of the pointwise and uniform convergence of power series.