“…Concerning tasks aiming to generate mathematical classroom discussions, research suggests that the tasks should: focus on important concepts (Cline et al, 2013;Crouch & Mazur, 2001); focus on one key issue (Cline et al, 2013); be quite difficult (Cline et al, 2013;Crouch & Mazur, 2001); produce distributed answers (Cline et al, 2013); and draw on prior knowledge and ways of thinking, and connect these to new mathematics (Miller et al, 2006). Further, it is suggested that CRS tasks should focus on analysis and reasoning instead of calculation or memory recall (Beatty et al, 2006a;Cline et al, 2013;Lim, 2011). A more specific tactic is to have multiple defendable answers, or no answer (Beatty et al, 2006a;Hodgen & Wiliam, 2011;Miller et al, 2006).…”