Describing a secondary mathematics teacher's specialised knowledge of functions

Taking a case study into the specialised knowledge of linear functions demonstrated by a secondary teacher, we aim to demonstrate, and to raise discussion about, a set of methodological tools for organising and representing mathematics teachers' knowledge. The results are art of an ongoing study which employs the model of professional knowledge known as Mathematics Teacher's Specialised Knowledge. We also believe that the use of these tools help to demonstrate the effectiveness of the division of this knowledge into subdomains, and affirms the relevance of the descriptors defining their boundaries.