Dyslexia is a specialized term that describes a type of learning
disability that affects reading ability. The term is frequently used
when neurological dysfunction is suspected as the cause of the
reading disability.  Dyslexia refers to the selective impairment of
reading skills despite normal intelligence, sensory acuity, and
opportunity for instruction.  Dyslexia impairs the reader’s ability to
link the sound of the letter with the letter in print and process the
“language” in written form.  A dyslexic individual has problems
recognizing and recalling the sound that goes with a letter.  

    Several perceptual studies also suggest that dyslexic readers
process visual information much more slowly than their peers.  
Because of the slow rate at which visual information is processed,
and the difficulty linking sound to letters, dyslexic readers often
read slowly and inaccurately.

   Starting as early as preschool, key behaviors can signal a
potential reading problem down the road.  During the early
preschool years (ages 3 and 4), most young children are naturally
amused by rhymes and songs.  Many children at this stage are
learning to recognize letters, especially those in their own name.  
Signs that may pinpoint a potential reading disorder at this stage
include slow vocabulary growth, word finding problems, and
difficulty recalling directions and familiar routines.

    At around age four or five years old, most children realize that
words can be broken apart.  Children play with language and may
make up silly words and songs. By late preschool (ages 4 and 5
years,) most children recognize words that rhyme.  A child may
have dyslexia if they cannot recognize the letters of their name
(given that this has been taught), cannot remember letter names
over time, and cannot seem to learn simple rhyming songs (for
example, Row Row Your Boat, etc.).  Preschoolers who cannot
predict how an often-sung song or well-rehearsed rhyme will end
(for example,” This little piggy went to…?) may be at risk for
dyslexia, too.

    By the end of kindergarten, most emerging readers can identify
the beginning sound of a word and can match the first sound of a
word with another. Most children at this stage can identify how
many sounds are in a small word (for example, the word “he” has
two sounds).  Most children will know their letters and sounds by
the end of kindergarten and will begin to see that the sequence of
written letters is linked to the sequences of sounds in a spoken
word.  Clues to dyslexia include not understanding that words break
apart (for example, “toothbrush” is “tooth” and “brush” together) or
not remembering the sounds that go with letters.

    By first grade, most children can identify the number of sounds
in longer words and can figure out what a word would be if a
specific sound was taken away (for example, take the “c” sound
from “cat” and you have “at”). Children at this age begin trying to
sound out unknown words with sounding-out approach.  Most
children have a sight reading vocabulary of 300 to 500 words by
the end of first grade and can understand simple written directions.
Children with dyslexia cannot isolate sounds in words, match
beginning and ending sounds, master common sight words, or
break apart words.  Children with dyslexia may also read words in
wrong order (for example, misreading “act” as “cat”) or may still
mistake letters (for example, confusing /b/ with /p/).

    By second grade, most children learn how to break up words
into syllables.  Remember clapping in school to see where the
syllables were? Children with reading disorders have a really
difficult time understanding where the words break apart. By the
end of second grade, most children can read smoothly and without
much hesitation in grade-level books. Dyslexic children take “wild
guesses” at words, skip over words by mistake, or lose their place
on a page. Children with dyslexia are often hesitant to read aloud
and stumble on longer words.

    By third grade, most children are reading smoothly even if they
are slow readers.  Children who are dyslexic, though, read with a
“choppy” pace, skip words by mistake, or lose their place on a
page. They still have difficulty with vowel sounds. Dyslexic children
may make errors when reading by “substituting” words that make
sense with the sentence but do not reflect the letters of the word
(for example, misreading “shirt” for “sweater”). Children who are
struggling to read often avoid reading by this time, saying that they
do not like to read, and may painstakingly try to “memorize” books
so that they can say them aloud without really knowing how to read.

    By fourth grade, most children can break words into prefixes to
guess at the meanings.  Children at this age can summarize what
they have read in grade-level text. Children who are dyslexic do not
seem to realize that words can be broken apart to identify meaning,
cannot tell a story back after reading it, and spell poorly.

    By high school, most readers read with adequate pace,
comprehension, and retention. Dyslexic students, though, read
very slowly and demonstrate difficulties in other subjects that can
also signal “red flags.”  Dyslexic students have a lot of trouble
memorizing, often struggle in foreign languages, and make
frequent spelling and grammar errors in their writing. Clues to
dyslexia include word finding difficulties, mispronunciations, and
fatigue when reading.

    In college, dyslexic students often read slowly, have difficulty
comprehending written text (even though they understand the
concepts when they are discussed orally), and have trouble
recalling facts, terms, and concepts from books.