What dyslexia is - and how to spot the signs
Dyslexia is one of the most common specific learning difficulties, and one of the most misunderstood. This page explains the current definition used in UK assessment practice, and the markers to look out for at different ages.
How dyslexia is defined today
UK assessment practice, as set out by SASC (the SpLD Assessment Standards Committee), is now guided by the definition produced by the 2025 Delphi study - a landmark consensus project in which dyslexia researchers, specialist teachers, educational psychologists and people with dyslexia agreed a shared, evidence-based description of the condition (Carroll, Holden, Kirby, Thompson & Snowling, 2025).
Key points from the definition include:
- In dyslexia, some or all aspects of literacy attainment are weak in relation to age, standard teaching and professional expectations.
- Difficulties with reading fluency and spelling are central features across ages and languages.
- The processing difficulties involved can include phonological processing (working with the sounds in words), working memory, processing speed and orthographic skill - and these vary from person to person.
- Dyslexia exists on a continuum: it can range from mild to severe, and it can affect people differently at different stages of life.
- Dyslexia frequently co-occurs with other developmental difficulties, such as developmental language disorder, dyscalculia, ADHD and developmental coordination disorder.
A set of processing difficulties that affect the acquisition of reading and spelling.
The Delphi definition of dyslexia (Carroll et al., 2025)Signs to look out for
No single sign means a child is dyslexic, and every dyslexic learner is different. But when several of these markers appear together and persist over time - especially in a child who is otherwise able - it is worth investigating further.
Primary-aged pupils
- Slow to learn letter names and letter–sound links
- Difficulty blending sounds into words, or breaking words into sounds
- Reading is slow, effortful or inaccurate - words may be guessed from pictures or context
- Difficulty with rhymes, and with sequences such as the alphabet or days of the week
- Spelling is erratic - the same word may be spelt differently on the same page
- Persistent letter confusions or reversals (such as b/d) beyond the age peers grow out of them
- Written work doesn't reflect the child's spoken ideas and vocabulary
- Trouble remembering and following multi-step instructions
- Difficulty copying accurately from the board
- Avoids reading aloud; tires quickly during reading and writing tasks
- Growing reluctance or anxiety around literacy, despite effort
Older pupils
- Reads accurately but slowly, and needs to re-read to take in meaning
- Still avoids reading aloud wherever possible
- Spelling remains weak despite years of effort and good teaching
- Written work is brief or disorganised compared with the quality of their spoken ideas
- Slow writing speed - struggles to finish tests and exams in the time allowed
- Difficulty taking notes while listening, or copying accurately under time pressure
- Finds planning and structuring essays and longer tasks difficult
- Misreads exam questions or instructions
- Difficulty learning vocabulary in modern foreign languages
- Relies heavily on memory aids, routines and technology to keep up
- Fatigue, frustration or dips in confidence around written work