The task-based lesson design consists of five phases. (See Figure 1.) 1) An a priori, or
pre-activity analysis identifies mathematical strands, big ideas, and key concepts that inform the
overall sequencing of the lessons as well as the individual task construction. 2) Specific tasks
are designed to flesh out the instructional sequences. 3) Students process the tasks during smallgroup
work, followed by a whole-class discussion. 4) Student solutions and classroom
observations from the implemented lessons are analyzed and the mathematics is further
unpacked where necessary to understand the students’ strategies. These reflections may prompt
a further reiteration of design and implementation (design cycle). 5) The task and an
accompanying selection of student solutions are written up as a set of Teacher Notes that