Mom of three fully functional adults who survived 12 years in Decatur School District #61.
All three of mine did full-day, five-day-a-week kindergarten. The eldest was only two days past her fifth birthday when she started, and she did just fine.
And yeah, they teach them things in kindergarten that my generation only got around to in the first grade, so if your kid basically doesn’t “do” kindergarten (and “full-time” is what counts as “doing” kindergarten), then yeah, she’s going to be behind in first grade.
I was actually shocked that they had my eldest copying entire sentences off the blackboard into journals by the second semester. In my day, kindergarten was for doing wooden puzzles and learning the alphabet and learning how to use scissors and glue, but nowadays the assumption is that preschool is the place for that, and generally the kids have to know their alphabet, colors, and how to use scissors and hold a pencil before they even enter kindergarten. In kindergarten nowadays they have them reading out of books (“Fun In The Mud”) by January, whereas in my day, you were still working on your ABCs.
So if she’s only going to be there a couple days a week, you’re going to have to tutor her at home so she won’t be totally lost when she does show up.
Kindergarten is also where you learn valuable social skills, such as what to do about the kid next to you who copies off your paper, and how to survive in a lunch room. If she’s only there part-time, she’ll miss out on a lot of that.
Kindergarten is where you learn to make new friends, too. It’s like at Army boot camp, you’re all n00bs together. But if she’s only there part-time, she’s not going to fit in the same way, being essentially a “visitor” every time she shows up. And when first grade starts, all the other girls will be greeting old buddies from kindergarten, and she’ll be, in essence, the New Kid, all over again. But if she’s there all the time, she gets to be an Insider.
And the all-day-every-day regimen of school is physically demanding if you’re accustomed to only going to school a couple days a week. If she’s not used to it, her first week of first grade is going to be brutal.
So all in all, if she spends her kindergarten year basically doing another year of two-day-a-week preschool, albeit very advanced preschool, she’s going to be totally swamped the first few months of first grade: new schoolwork that she can’t do or is unfamiliar with, being a stranger, being physically more tired than she’s ever been in her life, not understanding the unwritten ground rules and niceties of lunchroom, gym class, bus, hallway and locker etiquette, and recess.
She may also not be challenged much, mentally, by doing another year of preschool. IME, age 5 is the age of beginning to explore boundaries, not quite as much as a Four or a Six, but still, it’s the beginning of the formative borderline years of Five and Six between Preschooler and Big Kid. So spending a couple days a week at school is probably going to bore somebody who’s ready for much more.
So yeah, I’d definitely get her into the all-day-every-day kindergarten. Let Grandma pay for this. Her granddaughter needs it.
And yeah, if your daughter doesn’t pass those tests in third grade, she will be held back. It’s the whole “no child left behind” accountability thing. IME school districts don’t do automatic social promotion anymore, because they’re fearful of having it come back to bite them later.