[Show abstract][Hide abstract] ABSTRACT: This paper describes the make-up of interactive computer simulations that implement virtual laboratories in the field of Control Engineering education. We introduce Easy Java Simulations (EJS), a Java-based tool designed to help control educators with a low profile in programming to create interactive scientific simulations. This tool can be used on its own, generating stand-alone Java applications or applets, or in conjunction with MATLAB/Simulink, using them as the internal engine that describes and solves the model. This tool allows users to develop complete, interactive simulations in three steps: writing the mathematical model (optionally using MATLAB/Simulink), building the graphical user interface (GUI) using off-the-shelf graphical elements, and linking the GUI elements to the variables of the model. In this way, models of control engineering can be specified either using the programming support provided by EJS or by using MATLAB/Simulink, which can then be fully controlled from EJS. In this paper we describe this particular feature in detail, and provide some examples that show the advantages that this tool offers to the world-wide engineering education community.