Structure and fluid models need to be combined, orcoupled, when problems of fluid-structure interaction (FSI) are addressed. We first present the basic knowledge requiredfor building and then evaluating a simple coupling. The approach proposed is to con-sider a dedicated solver for each of the two physical systems involved. We illustrate thisapproach by examining the interaction between a gas contained in a one-dimensional cham-ber closed by a moving piston attached to an external and fixed point with a spring. Asingle model is introduced for the structure, while three models of increasing complexityare proposed for the fluid flow solver. The most complex fluid flow model leads us tothe arbitrary Lagrangian Eulerian (ALE) approach. The pros and cons of each model arediscussed. The computer implementations of the structure model, the fluid model, and thecoupling use MATLAB scripts, downloadable from either http://www.utc.fr/∼elefra02/ifsor http://www.hds.utc.fr/∼boufflet/ifs.