Three sample object oriented languages were selected to illustrate the important concepts in object orientation. Obliq is a simple yet clean and powerful interpreted OO language. It has a short learning curve and, with a few simple constructs, it can implement most existing object models found in much more complex languages. C++, as described by its conceptor, is an engineering compromise. Some functionality and elegance were sacrificed in favor of compatibility with C and performance. Nonetheless, it remains the most used object oriented programming language and thus deserves our attention. Modula-3 is an excellent vehicle to teach advanced concepts and implement efficiently complex distributed interactive systems.