If you have a kid who goes to kindergarten and doesn't know what a circle is, doesn't know what red and green are, and doesn't know what right and left are, by the time he learns those things, the rest of the class is far ahead of him.
My husband and I have known each other since kindergarten. I had a crush on him in school, but we never dated. Then we saw each other again after high school, and there was something instantly familiar about him. I'm a very shy person and was very closed off. But he allowed me to be myself. And there's a safety in that.
Harper Lee and Truman Capote became friends as next-door neighbors in the late 1920s, when they were about kindergarten age. From the start, they recognized in each other "an apartness," as Capote later expressed it; and both loved reading. When Lee's father gave them an old Underwood typewriter, they began writing original stories together.
In kindergarten, you can learn how to be a citizen of the world.
I have two daughters, and we live here in Manhattan, and having gone through the Manhattan kindergarten application process, nothing will ever rival the stress of that.