For a long time, we have thought of effective assessment as being timely and specific. But what do we really mean by this, and is this type of assessment truly effective? In this session, we will interrogate these views for both effectiveness and feasibility. We will also explore a different perspective on effective feedback and assessment, rooted in Peter Liljedahl's Building Thinking Classrooms framework. This approach will allow us to construct a more comprehensive understanding of assessment that supports deep mathematical thinking and student autonomy. Prior knowledge of BTC is not necessary to attend this session.