I've developed this resource to help explain my assessment to parents and other teachers. Using a phonological deficit definition of dyslexia (for example Frederikson and Frith, 1998; Hedman, 2012), the core feature I look for is a weakness in phonological processing skills (the central circle). The second circle contains "symptoms" which are common, although not all people with dyslexia will display all these characteristics. The third circle shows more characteristics, although these again vary from individual to individual. The words around the outside describe co-morbid conditions, which do not define dyslexia, but are often associated with it. I've included Frith's (1999) framework for describing SEN as a further tool to help explain where these things can be observed and the part that environment can have in interacting with a pattern of strengths and weaknesses.