Comprehension of concepts and algorithms involved in the robotics field can be improved through the use of an interactive visualization tool. The motion planning problem consists of finding a valid path between a start and a goal configuration for a movable object or robot. The workspace, in traditional robotics and animation applications, is composed of one or more objects (called obstacles) and a robot. In this paper we present an interactive tool for visualizing and editing motion planning environments, problem instances, and their solutions to help students in their understanding of the motion planning problem in robotics related courses. Teachers can take advantage of visualization tools to help their students to better understand motion planning and its complexity as well as the different strategies that have been developed to solve the motion planning problem. While the tool we present allows the manipulation and evaluation of planner solutions and the animation of paths found by motion planners, it is specialized for randomized planners that use the Probabilistic Roadmap Methods (PRMs) or tree-based methods.