Teachers commonly report experiencing difficulties in incorporating problem solving and reasoning into their mathematics classrooms (Stacey, 2010) while at the same time catering for students with a wide range of prior experiences (AustralianCurriculum and Assessment Reporting Authority, 2010). Rather than the common approach of starting learning sequenceswith simple tasks intending to move to more challenging tasks subsequently (see Tzur, 2008), we are exploring an approachbased on initiating learning through a challenging task—described as activating cognition. In particular, we describe theimplementation of a particular lesson structure designed to initiate learning through an appropriate challenge, effectively differentiating that challenge for particular student needs, and consolidating the learning through task variations.