Research suggests that teachers of mathematics are frequently reluctant to pose challenging tasks to students. Reasons for this reluctance include fears of negative student reactions, time and resource constraints, and a lack of relevant teacher content knowledge. The current study involved interviewing three early primary-grade (elementary) teachers to explore their perceptions of teaching with challenging tasks, following their observations of 2 units of mathematical work taught by the first author. Contrary to some other studies where classroom teachers were themselves observed teaching with such tasks and asked to reflect on the experience, we found that teacher-participants perceived that students responded positively to the 2 units of work. Specifically, teacher-participants described their students as autonomous, persistent and highly engaged. These positive student reactions were attributed to a variety of factors, including a classroom culture that embraced struggle, high teacher expectations, and consistent classroom routines. Despite these positive reflections, teacher-participants differed in their views of whether challenging tasks are a suitable means of differentiating instruction, with such evaluations apparently linked to how they defined student success.