Estimation is such an important yet sometimes overlooked skill. Enhancing estimation skills through exposing students to enumeration ('how many') problems where they are required to estimate before calculating is a critical aspect of developing number sense (Reys et al., 2012). This article describes a 'how many' problem undertaken with a small group of Year 1 students (identified by their teachers as high-performing), in which students were given repeated opportunities to refine their estimates as additional information became available. This can be described as dynamic estimation, and is presented as a counterpoint to the idea that estimates should only occur at one point in time (i.e., before beginning a problem), typically when very little information is available to students. Although the activity as it is discussed in this article is confined to estimates in relation to a container of counters, it could easily be replicated using a more engaging, context-rich, enumeration task such as an outdoors maths lesson counting sheoak cones (Parrington & Millar, 2018).