She would be one of the older kids in 2021 or could choose to play 2020 (if that's what class she's in -- in NY, she would be age appropriate for the class of 2020, but in almost every other state in the country, she would be age appropriate for the class of 2021)
What throws off so many people on this board is the assumption that most states use a calendar year cutoff for school grade, when in fact most states use Sept 1 or Oct 1 for cutoff. NY and CT are just about the only states that generally use Jan 1 as the cutoff.
