References
Bills, C. (2002) ‘Mental mathematics’ in Haggarty, L. (ed.), Aspects of Teaching Secondary Mathematics: Perspectives on Practice, London, Routledge.
Mason, J. (1988) ‘Imagery, imagination and mathematics classrooms’ in Pimm, D. (ed.), Mathematics, Teachers and Children, Sevenoaks, Hodder and Stoughton.
The Open University (1988) ME234 Using Mathematical Thinking, Block 1 Investigating Mathematics, Unit 2 Working Mathematically, Milton Keynes, The Open University.