On Wednesday, a coalition of private school choice opponents gathered at the Statehouse and accused the Legislature of ignoring the state Constitution — which mandates a common system of free public schools. It’s a throwback from the 1990s and early 2000s, and a marathon school facilities lawsuit. And opponents of House Bill 93, the $50 million private school tax credit law, are pinning their case on this one sentence. And even more narrowly, on a single little word in this sentence: “a,” as in “a general, uniform and thorough” education system. “Not surprisingly, school choice advocates do not attach the same significance to the word “a” — or the “uniformity clauses” that are commonplace in state constitutions.