Great emphasis has, in recent years, been placed upon the interactive use of computers in electrical engineering education. In particular, a number of successful programs have been written in A Programming Language (APL) to demonstrate and explore various aspects of power-system analysis. Most of these programs, however, routinely require the specification of a network's topology and a number of base-case operational parameters on the part of the user. The authors have developed an interactive APL power-flow demonstrator according to a different philosophy. All calculations are performed upon a small two-generator system which contains all the essential components of a large practical power network. The network itself, with all its parameters, is shown graphically on the CRT screen or by the printer, and the displayed parameters are updated automatically as calculations are performed. Using this small network, students are able to observe the effects of changes in network parameters and operating strategies upon the voltages, currents, and power flows. A major use of this program is to enable the student to ultimately learn how to adjust certain operating parameters in order to cause others to be within specified tolerances. The program and its underlying philosophy are described and illustrated, and typical examples of its use are presented.