Why do children go un-noticed?

Why are so many struggling students not noticed until about Year Four and beyond?
At about Year Four, there is a marked increase in the number of children referred for reading assistance (Chall, Jacobs, & Baldwin, 1990). This may represent the dawning of teachers' recognition that the maturational delay hypothesis can no longer be used to explain the lack of reading progress. More salient perhaps is the generally unacknowledged explosion of new words in textbooks at about that time (Carnine, 1982) and of the increased complexity of the words in those texts (Henry, 1991).

Many students who have relied upon whole-word memory recognition as their mode for storage and retrieval find the strategy collapses in Year Four. Whereas, a word recognition capacity of 400 words is adequate for coping with text up to this time (and many children's visual memory can manage such a load), the demand increases dramatically to about 4000 words around that year, and up to 7000 words by Year Six (Carnine, 1982), what Share (1995) describes as an "orthographic avalanche" (p.17).

For the student who relies primarily on word shape, the task is similar to that required in visually memorizing 7000 telephone numbers. In those languages that do rely on images rather than an alphabet for their construction, the number of words that are typically employed in print is far less than in English. For example, Chinese adults are said to have a working familiarity with only about 4000-5000 (Adams, 1990). Students who cannot access the phonological route to identify the escalating array of new words obviously struggle, and progress grinds to a halt.

In truth, they had difficulties before this time, but perhaps managed to disguise them in classrooms where careful continuous assessment of word attack skills was unavailable. Unfortunately, this under-identification appears to be even more likely for girls, as their rate of referral for assistance (about 1 in every 4 referrals) does not match the prevalence (about equal with males) of reading problems among females in our society (Alexander, Gray, Lyon, 1993). 

Taken from "Addressing Reading Failure at the Secondary Level: Problems and Issues" Thornbury-Darebin Secondary College Thursday 25/10/2001

Still relevant today.