We develop a scheme for representing critical non-functional requirements (NFRs), and apply it to the domain of multimedia educational software (MES) to validate it. Our approach extends the model for representing design rationale by making explicit evaluation goals, providing the means to improve the quality of MES. Further research issues will be discussed including the need to relate NFRs to the architectures and a set of architectures to an application domain. Keywords Architecture, Design rationale, Educational software, Multimedia, Non-functional requirements