This report describes the design, development, implementation, and evaluation of a web-based tutorial designed to teach graduate students about the statistical concept of power. It contains a literature review of techniques used to teach statistics, similar computer-based programs for representing the concept of power, and instructional theories that pertain to web-based tutorials. It describes the process of designing and developing this tutorial in detail. The results section contains a description of the product implementation with three different groups and discusses the qualitative and quantitative findings from each of these implementations. Finally, there is a discussion of the tutorial's strengths and weaknesses.