I tutored reading in a public school, which was fairly diverse with many kids (maybe 40 percent?) on free or reduced lunch. By the middle of first grade, "average" was probably kids reading 30 words per minute of first grade level text, like "The cat ran by the tree." A lot of kids were still working on sounding out basic words. I looked briefly at test scores for reading fluency and there were very few kids who were fluent readers. That being said, when DD was moved to first grade from Kindergarten, in Nov. of that year, I would say about 1/3 of the class was reading chapter books, like Magic Treehouse or Junie B Jones or something along those lines. We are in a somewhat higher SES school, maybe 25 percent free lunch? I think it was a higher performing class than some of the other teachers had. So you never know until you actually see the class. You didn't ask about math, but for math most kids are still working on basic addition/subtraction up through 20, like 5+7 and they don't do much beyond that. It was a dismal situation for DS this last year, who was in first grade able to easily multiply and divide. His teacher ultimately threw out the first grade curriculum and had him do work based on above-level testing.
For writing, the kids were expected to write short paragraphs, but nothing really more than that (although a lot of it was journal writing and they could write what they wanted).
