Developing an adequate understanding of the nature of science includes developing an understanding of the uses and importance of models in science. General accounts of science aimed at university students, however, tend to neglect this aspect. A noticeable exception is the simple model of the key elements of a scientific result presented by Giere, Bickle, and Mauldin in their book "Understanding Scientific Reasoning" (2006, Ch. 2). The model--referred to here as the Giere model--is a valuable tool in nature of science teaching that aims to help university-level science students understand "how" scientists can claim that a result is justified and to evaluate "whether" this is in fact the case. However, students tend to have difficulty applying the model to real cases. This is partly due to ambiguities and (over)simplifications in the model. This paper therefore aims to improve the applicability of the Giere model under its original scope by clarifying and nuancing key concepts in the original model. Furthermore, the paper aims to adapt the Giere model to make it applicable to knowledge claims about the results of scientific design.