There is a lack of practice sessions in distance learning courses, in which students can use the theoretical concepts seen in class. In this paper we present an implementation of a Robotics Virtual Laboratory in a Networked Virtual Environment (net-VE) with the capability of defining practice sessions that can be executed in a visual simulation of the environment. Several manipulator robots, mobile robots and furniture can populate the environment. A programming language for manipulators and mobile robots is presented. The language contains instructions to provide coordination between robot programs; an interface for defining a task as a set of conditions for executing programs has also been implemented. Teachers can assist students either by collaborating during the execution of the practice or writing a rule-base script for observing movements of the robots.