> which republics are missing from the public education diet? Both Athens and Rome are studied to death in public school. Sparta wasn't a republic (or anyone's idea of a model for a good, or successful society.)
Athenian democracy is discussed, but nots its constitutional structure and evolution. Sparta wasn't a republic, but it had elected leaders. (If we want to split hairs: proto republics. Also, right here is a point missed by many: elections a democracy do not make.) Similarly, at least my American education about Rome focussed on the fall of the empire--not the the republic.
Adding to the traditional corpus: the Vajjika League [1], Carthage, the maritime republics, Britain, the Haudenosaunee f/k/a Iroquois. Possibly also confederacies: the Holy Roman Empire, the Swiss, et cetera. Finally, other extant constitutional systems. Basically, how do the bones of government work, what have we tried, what are we trying, and what lessons can we draw from the past.
> anyone's idea of a model for a good, or successful society
There is merit to studying failed societies. The Spartan Gerousia bears striking resemblance to certain ossified structures in modern governments.
Sparta wasn't a republic (or anyone's idea of a model for a good, or successful society.)