This post from Professor Terry Cavanaugh about the importance of font size for struggling readers is no longer available on Teleread.com, but the excerpt below shows what he had to say.

“Actually font size change is important for many who have print disablities, not just that it could be done. One of the first things that we try to do for students with disabilties is get all the texts that they use in a digital format if possible. Screen maginifaction just doesn’t do the same thing as it impeeds saccades and fixations in the reading process.

“As the print is made larger, students view fewer words on the page, thus enabling them to focus more easily and decrease the chance of losing their place while reading – something that is easy to lose while moving with magnification. Larger print is also important when reading at a greater distance, at lower light levels, and when moving. While the use of large print text has usually been associated with assisting the special needs of students with visual impairments or older people, the benefits gained with the use of large print are actually applicable to others who may not have a learning disability, specifically the struggling, reluctant, and remedial readers.

“Font size, paper and ink colors, and formatting are several factors that all have an effect on readability of text material. especially those susceptible to visual stress, were found to make more errors on the smaller than on the larger text. From this Hughes and Wilkins (2000) concluded that the reading development of some children could benefit from a larger text size and spacing than is currently the norm. Reading miscues, including misreading syllables or words; skipping syllables, words, or lines; rereading lines; and ignoring punctuation cues were found to be virtually eliminated when students read large print books.

“Fewer words on a page mean struggling readers have to visually process less per page, but it still allows the readers to make progress with comprehension, tracking, and fluency, with fewer decoding errors. Additionally, having fewer words on the page lowers anxiety levels concerning the text in struggling readers. The ability to change to a larger print provides a positive and powerful tool for struggling, reluctant, and visually challenged readers. Increased font size and spacing of large print scaffolds struggling readers to develop the skills they need. Larger print assists students in: recognizing words accurately, comprehending what they are reading, and reading more fluently.

“Currently many teachers and librarians already use large print materials for their students who have:
* Attention Deficit Disorder (ADD)
* Difficulty with encoding or decoding
* Dyslexia
* Large or small motor deficits
* Amblyopia or “Lazy Eye”
* Light sensitivity
* Short term memory deficits
* Tracking issues
* Visual impairments”