That's what Taz says he does "in school" every day.
I beg to differ ...
It's interesting (and maybe even a little sad) that even my own little kindergartener thinks that only sit-down, teacher-directed work "counts" as "school!" That's such a small part of it. Sure, he'd likely never know the names of the alphabet letters or the sounds they symbolize, unless someone exposed him to it. Same for recognizing numerals (though not number concepts!). But "exposure" is really all it takes. The real learning comes as those little wheels start turning all on their own, in response.
I am absolutely convinced that little children learn most from their own calm, rich exploratory play, especially when the environment (and a responsive, attentive adult) is set up to facilitate it. That, and lots of wonderful picture books. And fingerplays and songs. And fun, silly games -- with the people who love them best. That's what I'm aiming for, anyway.
And that, to me, is what "school" ought to be.