The National curriculum advises that pupils who have reached the expected standard should not move on to new content but develop understanding at greater depth. Teacher subject knowledge is a key part of securing greater depth. Participants will increase their understanding of the meaning of greater depth in the context of mathematics, the ‘concept’ of greater depth and the ‘label’ as used in the current interim frameworks for teacher assessment. Participants will also explore questions and activities that promote greater depth in mathematics, curriculum design ideas that challenge many established ideas of effective mathematics teaching and the four ‘corners’ of greater depth in mathematics.