“…Turning to understanding, whilst it is often cited as a particularly valuable epistemic state (de Regt, 2009;Grimm, 2012;Smith & Siegel, 2004), perhaps because of ongoing debates about the nature of the concept itself (de Regt et al, 2009;Grimm et al, 2017), there is a lack of consensus about how understanding in general, and therefore NOS understanding in particular, might be assessed. If a model of understanding as an appropriately connected conceptual structure (Elgin, 2007;Kvanvig, 2003) is adopted, NOS understanding assessment approaches might examine the inter-relationship of knowledge elements elicited from multiple choice probes (Mulvey et al, 2021;Peters-Burton et al, 2019), open-ended responses (Koksal & Cakiroglu, 2010), comments in interviews (Zimmermann & Gilbert, 2010) or essays (Allchin, 2011). Given the graded nature of understanding, when reporting NOS understanding, students' achievements might be described on a continuum, for example, shallow, partial or deep understanding.…”