Communication theory is one of the subjects that is mathematically intensive and involves memorizing numerous equations. This paper describes the use of Matlab and Simulink in teaching communication theory for undergraduate students. The objective of this approach is to provide an intuitive understanding of the theory without deeply sinking into derivations of formulae. Signal filtering is an inevitable step in every communication system. Generally, filter theory is a standalone course offered to graduate level students. Using amplitude modulation as a case study, usage of Fast Fourier Transform (FFT) is discussed in this paper. Frequency domain representation of a signal and ideal filtering that can be performed directly without applying much involved z-transform is presented.