My littlest sister didn't learn how to read until she was 7 or 8. She was the youngest of four, and the rest of us had all gone through a strict Catholic school that had you reading in first grade like it or not. Calla, however, went to a comfortable, granola-y neighborhood schoolhouse that was much more relaxed. My mother didn't know whether she had a learning disorder or whether she was just doing it at a more natural rate. If Calla had been the first child, instead of the fourth, she probably would have had lots of intensive attention. Her teacher was recommending lots of tests for placement in special education. But what happened is that my parents just pulled her out of school for a year to homeschool, with weekly visits from a reading tutor and lots of free time for herself... and she just sort of taught herself to read.

OK, I just found the post in my mother's livejournal (devils_interval) where she talks about this, instead of me just parroting what I remember her saying to friends at the time. Here:

This is the kid who could not, despite hers and our best efforts, read when she was eight. We had tutors, we had assessments...then in desperation I took her out of school for a year during which she spent most of her time lying on her bed reading Spider magazine. Or trying to. And then, like magic (because her tutor had taken a full-time job and she wasn't being tutored at the time) she started reading with a depth that was way beyond her chronological age. In April she was still struggling through Little Bear books; in summer when the 4th Harry Potter book came out she spent a whole week catching up. In a week she read the first three and then the 4th book.

I guess what I mean is, don't panic; it's definitely possible that Casper's brain is just taking her own pace, and doesn't mean she won't read as well or as happily as other kids once she gets there.

(Sorry for the edits!)