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Dyslexia Handbook

Definition of Dyslexia Facts about Dyslexia Signs and Characteristics of Dyslexia Myths and Misunderstandings about Dyslexia Student Support

MCPS is providing this Dyslexia Handbook as a resource for educators and families who are supporting students with dyslexia.

This resource reflects a district-wide commitment to serving students with dyslexia by raising awareness about the learning disability and providing appropriate instruction and academic support and resources that will foster academic success and social-emotional well-being for students with dyslexia.

Dyslexia Handbook

Definition of Dyslexia

Dyslexia is a Specific Learning Disability that specifically impacts reading, spelling, and reading fluency. It is described as a word-level reading/spelling impairment. While other common characteristics accompany dyslexia, acquiring fluency with word recognition and spelling is the major impact.

The International Dyslexia Association provided an updated definition in October 2025:

Dyslexia is a specific learning disability characterized by difficulties in word reading and/or spelling that involve accuracy, speed, or both and vary depending on the orthography. These difficulties occur along a continuum of severity and persist even with instruction that is effective for the individual's peers. The causes of dyslexia are complex and involve combinations of genetic, neurobiological, and environmental influences that interact throughout development. Underlying difficulties with phonological and morphological processing are common but not universal, and early oral language weaknesses often foreshadow literacy challenges. Secondary consequences include reading comprehension problems and reduced reading and writing experience that can impede growth in language, knowledge, written expression, and overall academic achievement. Psychological well-being and employment opportunities also may be affected. Although identification and targeted instruction are important at any age, language and literacy support before and during the early years of education are particularly effective.

The United States Congress passed a Federal Statute in 2019 as part of a bill to recognize the disability and name October as Dyslexia Awareness Month.

Dyslexia is an unexpected difficulty in reading for an individual who has the intelligence to be a much better reader. It is commonly caused by a difficulty in phonological processing which affects the ability of an individual to speak, read, and spell. Dyslexia is the most common learning disability, accounting for 80-90% of individuals with a learning disability. Dyslexia impacts 1 out of every 5 individuals.

Dyslexia is a paradox in that an individual may have both

  1. Weaknesses in decoding that result in difficulties in accurate or fluent word recognition
  2. Strengths in higher-level cognitive functions, such as reasoning, critical thinking, concept formation, and problem-solving.
  3. Strengths in higher-level cognitive functions, such as reasoning, critical thinking, concept formation, and problem-solving.

The achievement gap between typical readers and dyslexic readers occurs as early as first grade.

The achievement gap between typical readers and dyslexic readers occurs as early as first grade.

Early screening for and early diagnosis of dyslexia is critical for ensuring that individuals with dyslexia receive focused, evidence-based intervention that leads to fluent reading and the provision of necessary accommodations that ensure success in school and life.

Both of these definitions describe dyslexia as a learning disability that impacts fluent reading and learning to read. The language in the Federal Statute describes the disability as “unexpected” to highlight that dyslexia is not influenced by levels of intelligence or other cognitive strengths. Average to above-average intelligence and cognitive strengths are not required criteria for dyslexia. While this consideration is highlighted because high intelligence and cognitive strengths can mask dyslexia, this is not the only profile of students with dyslexia.

Facts about Dyslexia

  • Dyslexia is a Specific Learning Disability that impacts 10-20% of the population. It accounts for up to 80% of all identified SLDs.
  • Dyslexia is highly heritable. Dyslexia runs in families. While it is possible to have dyslexia without a family history, those with a family history are very likely to also have dyslexia.
  • Dyslexia is neurobiological. Dyslexia is a brain difference that is included in what is called neurodiversity.
  • Dyslexia is caused by a Phonological Core Deficit, a localized weakness in a specific component of the language system in the brain. This impacts the ability to appreciate the internal sound structure within words.
  • Dyslexia can be caused by slow Naming Speed. Naming Speed is a specific type of processing speed in the brain that attaches vocabulary to a visual stimulus. This impacts a student’s ability to learn and remember letter names and sounds and also develop reading fluency.
  • Dyslexia may be unexpected. It is common for students with dyslexia to have great intellectual strengths and high intelligence. This serves those with this profile to develop compensatory strategies. This also can mask the identification of the disability, especially without specially designed screening tools.
  • Dyslexia is a spectrum disorder, which means it varies in impact. Students can have mild, moderate, or severe dyslexia. The level of impact caused by a Phonological Core Deficit and/or Naming Speed can vary. There is no one consistent profile for dyslexia. Students with dyslexia will have difficulty with reading, spelling, and/or reading fluency.
  • Dyslexia is often paired with one or more coexisting conditions. These include ADHD, Dysgraphia, Dsycalculia, Developmental Language Disorder, and Anxiety Disorder. ADHD alone can greatly impact reading and writing skills as it includes weaknesses in attention, ability to focus, metacognition (being aware of thinking and learning), working memory, and self-control. DLD alone can greatly impact reading and writing skills as it causes delays in understanding and using language. When these SLDs are paired with dyslexia, a student’s learning profile becomes more complex.
Facts about Dyslexia

Signs and Characteristics of Dyslexia

Primary characteristics are caused by a Phonological Core Deficit that includes weaknesses in Phonemic Memory, Phonemic Awareness, and the ability to learn phonics skills. Slow Naming Speed impacts retrieval for letter sounds and words.

Primary characteristics:

  • Difficulty learning letter names and sounds
  • Difficulty decoding
  • Difficulty spelling
  • Word reading accuracy
  • Reading fluency

These primary characteristics are all components related to written language. Deficits in these areas can lead to additional language deficits and secondary consequences.

While these are the primary shared signs and characteristics of dyslexia, there are other signs in a child’s development that could indicate risk for dyslexia. These include:

  • Family history
  • Late establishment of hand dominance
  • Late to talk
  • Difficulty reciting the alphabet, days of the week, popular rhymes, counting
  • Difficulty rhyming, anticipating the rhyme in a rhyming text
  • Mixing up the sounds in words when speaking (beddy tear, medicine, emeny, officer)
  • Confusing similar-sounding words when speaking (swirl and squirrel)
  • Using general words like “things,” ”that,” “stuff” instead of precise vocabulary
  • Difficulty with rote memory tasks
  • Trouble with writing letters, spelling name
  • Breaking words into syllables and sounds
  • Difficulty learning math facts
Signs and Characteristics of Dyslexia

Secondary Consequences

Written expression

Writing can cause fatigue and frustration due to the difficulty with spelling. Writing stamina and word choice are therefore impacted and the ability to express ideas and understanding through writing is diminished.

Reading comprehension

Due to the cognitive demand decoding requires, less cognitive space is available for making meaning from text. Lack of fluency taxes working memory and reading comprehension is compromised, despite having strong language comprehension skills.

Reading experience

The act of reading itself is difficult, slow, fatiguing, and frustrating for many with dyslexia and therefore those with dyslexia tend to read less than their fluent peers. This reduced reading experience impedes the development of content knowledge, vocabulary, and complex language.

Myths and Misunderstandings about Dyslexia

  • Students with Dyslexia won’t learn to read

    Students with dyslexia can and will learn to read with instruction supported by the Science of Reading which includes explicit, systematic, and cumulative instruction in Phonemic Awareness and Phonics. While all students benefit from this approach to instruction, students with dyslexia may need more frequency, intensity, and/or duration and opportunity to practice than neurotypical peers, depending on the severity of the dyslexia. With this appropriate dose of instructional time, most students with dyslexia will learn to read. Most may always have difficulty with spelling.

  • Students with Dyslexia see words backwards

    Reversals are common in most beginning readers. Attention to a letter’s orientation takes time and practice to develop. Errors in sequencing sounds in words are also common in beginning readers. Students with dyslexia, depending on the level of impact, may remain in that beginning reader stage longer than their peers. As a result, they may continue with these types of errors for a longer amount of time. Frequent reversals are not a visual processing problem. The trouble with learning to process and distinguish between mirror images causes reversals, not vision.

  • Dyslexia is rare

    Dyslexia impacts 10-20% of the population.

  • Dyslexia is a product of low intelligence

    Dyslexia is independent of intelligence. It is a brain difference that impacts those with all levels of intelligence.

  • Poor instruction causes Dyslexia

    While poor instruction can cause the primary characteristics of dyslexia, poor instruction can not cause dyslexia. Dyslexia is neurobiological and often genetic. Students without dyslexia can suffer similar consequences of dyslexia when deprived of quality instruction, but the neurological condition is not created by poor instruction.

  • Dyslexia can’t be identified in young children

    Risk for dyslexia can be identified very early.
    • Birth-2 years old: Family history and/or delayed onset of speaking skills
    • 3-5 years: Weak Phonemic Processing and Weak Letter Knowledge
    • 6-8 years: Weak decoding, word recognition, and spelling of one-syllable words. The slow rate of learning print skills, slow response to instruction
    Young children respond to intervention instruction best, so early identification of risk is essential for recognizing the need and providing early intervention instruction
Myths and Misunderstandings about Dyslexia

Student Support

It is difficult to navigate school with dyslexia. Most parts of the school day are rooted in text. Students with dyslexia often can not yet interact with text with the same proficiency as their peers. It is very important that students with dyslexia understand their disability, that it is specific to reading and writing, and that they can excel in all parts of school.

Learn about Student Support

MCPS Dyslexia Student Support