Educational activities involving antenna arrays to motivate the study of sinusoids are described. Specifically, using fundamental concepts related to phase and simple geometric arguments, students are asked to predict the location of interference nulls in the radiation pattern of two-element phased array antennas. The location of the radiation nulls are then verified experimentally. The activities have been employed both in a freshman-level electrical engineering course and, in expanded form, a summer research experience for high school students. Details of the experiments are given, as are results of student assessment and suggestions for further development.