One of the more interesting areas of problem solving in chemistry attempts to answer the question, "What do students understand about the molecular level of chemistry?" This question is also implicit in the more traditional area of mathematical problem solving but in this paper, more focus is placed on devising ways to help students develop a sound conceptual understanding of chemistry which includes molecular-level representations. It is suggested that having students express their understanding of the molecular level in drawings accompanied by written explanations is a powerful way of helping students shift their focus from the macroscopic (bulk property) level of matter to thinking about the nature of the invisible molecular world. This shift of focus seems to require a difficult transition in student thinking and the drawings seem to help students begin to make that transition. These drawings are also useful tools for the professor or TA (teaching assistant) to assess their students' understanding of molecular-level concepts. When drawing understanding of the molecular level, a great deal about what is known what is unknown about the molecular nature of chemistry is revealed. Therefore, these drawings can be useful in checking students' developing understanding (formative assessment) and determining students' level of understanding on an exam (summative assessment). This paper presents some of the ways in which molecular-level representations can be incorporated into a chemistry course. Based on the experiences, it is suggested that students view these representations in a variety of ways. Many students find them interesting and challenging. Others are incensed that chemistry does not simply consist of numerical problems. Still others think that a window has been opened to the molecular world for them. (Author/SOE)