This study investigated preservice science teachers' uses of inscriptions in their peer teaching activities and was guided by the following research questions: (1) What kinds of inscriptions and inscriptional practices do preservice science teachers use in their peer teaching activity? and (2) How and for what purposes do preservice science teachers use inscriptions and inscriptional practices in their peer teaching activity? This study followed a multi-participant case study approach. Video recordings of seven preservice teachers' lessons were analyzed for inscriptional use. Results indicate that preservice teachers used inscriptions in both pedagogical and normative ways, and the level of abstractness of inscriptions used varied across different science sub-disciplines. Our findings demonstrated that preservice teachers have multiple purposes when using inscriptions and that their purposes differ from scientists' purposes. Preservice teachers used inscriptions: to convey final form scientific knowledge; to engage students in scientific practice; to make thinking visible; to connect multiple ideas using multiple inscriptions; and to provide data or example from nature. In addition to these purposes, preservice teachers also used inscriptions as formative assessment, to engage students in the lesson and to review at the end of a lesson. We conclude that science topics and the different purposes of the sequences of activities could be responsible for the variety of uses of inscriptions across lessons. In addition, the different uses of inscriptions may impact students' understandings of scientists' inscriptional practices. Implications for science teacher educators incorporating inscriptional practices in science teaching methods courses are discussed.