“…Cognitive engagement is often associated with learners' attention and mental effort (Helme and Clarke, 2001;Philp and Duchesne, 2016), alertness (Svalberg, 2009), and noticing or discussion of language features (Baralt et al, 2016;Storch, 2008;Toth, Wagner, and Moranski, 2013), as demonstrated in language-related episodes or LREs (i.e., discussion of language forms), negotiation of meaning, elaborative talk (e.g., talk used to clarify and expand semantic meanings), and idea units (e.g., amount of ideas or content) (Dao & McDonough, 2018, 2019Lambert et al, 2017;Phung, 2017;Qiu and Lo, 2017). Behavioural engagement is perceived as learners' time on task or participation, operationalised as, for example, language production (e.g., amount of time on task, and numbers of utterances, turns, and/or words).…”