This paper describes how an undergraduate control course is enhanced with Sysquake interactive applications. Basic concepts in control theory, different ways to assess performance and robustness of a controlled system, and limits of closed-loop systems are illustrated with graphics which can be manipulated directly with the mouse, letting the student acquire a deeper and broader understanding of the theory. The applications, implemented with Sysquake as stand-alone programs, offer a simple user interface while supporting a wide range of problems.