Thinking together in primary classrooms has received much scholarly attention in recent years, with a focus on educational dialogue at the forefront of studies concerned with identifying what constitutes effective language for learning. Whilst the expression of explicit reasoning is often discussed, less attention has been given to the role that provisionality or vague language plays in supporting the articulation of 'thinking aloud in action'. In this study, we draw on data which comprised recorded lessons of primary-aged children (8-10 years old) in whole class and small peer-group learning contexts. Using linguistic ethnography we examine the data for patterns of specific vocabulary associated with reasoning and provisional or vague language. We then identify episodes in the transcripts where the language co-occurs. Tracking two children's contributions, we are able to note the differences in their articulation of ideas in the different learning contexts of whole class and small group. We conclude that not only is thinking aloud complex, fluid and provisional, but that 'epistemic modality' supports reasoning by allowing a tempering of proposed ideas and by appealing to listeners by referencing shared experiences. The small group or larger whole class contexts change this relationship, though not necessarily as expected.