The most widely accepted view of dyslexia has been that it can be considered to be part of the continuum of language disorders.  This view has gradually shifted more recently to a more specific theory: that dyslexia is characterised by phonological processing difficulties. 

Children with dyslexia typically have difficulties that primarily affect the phonological domain (mapping speech sounds onto meanings); the most consistently reported phonological difficulties are limitations of verbal short-term memory and problems with phonological awareness. 

There is also evidence that children with dyslexia have trouble with long term verbal learning.  This many account for many classroom difficulties, including problems memorizing the days and months, word finding difficulties and poor vocabulary development. 

These are all areas that speech & language therapy can help with.