This study focuses on teachers' use of informal formative assessments (IFAs) aimed at improving students' learning and teachers' recognition of students' learning processes. The study was designed as an explorative case study of four middle school teachers and their students at a charter school in the northeastern U.S.A. The data collected for the study included a history of teaching questionnaire, video records of the teachers' IFA practices, ethnographic interviews with teachers, and field notes from classroom observations. These data were analysed from a sociolinguistic perspective focusing on the ways that classroom discourse and reflective interview conversations constructed ways of viewing assessment. The findings from the analysis of the classroom discourse showed that teachers use three different types of IFA cycles, labelled as connected, non-connected, and repeating. Teachers' reflections on video cases show that teachers can learn to view in-the-moment interactions in new ways that can guide IFAs. We concluded that teachers' perspectives on the effectiveness of IFAs are an important, but often neglected, part of building a robust, interactive classroom assessment portfolio.