The Brooklyn KIPP school I’ve been focusing on isn’t the only KIPP school likely to get its first-ever labor contract, courtesy of the United Federation of Teachers. The teachers union is also pushing to negotiate a labor contract on behalf of teachers at KIPP Infinity, a middle school that got one of two of the highest grades in the city on the Department of Education’s progress reports last school year.

While the teachers at KIPP AMP in Brooklyn asked to be represented by the union, the teachers at KIPP Infinity are in a different situation. Randi Weingarten, the president of the union, told me on the phone today that the union has represented Infinity’s teachers for a while, as part of a deal through which the union provided them with health benefits through something called a “welfare fund.” (Not sure what that is.) But the union’s relationship with Infinity did not extend into the more confrontational territory of helping the teachers develop a labor contract.

Today, the union’s secretary, Michael Mendel, informed Infinity’s board members that the union wants to go there and negotiate a labor contract. Here’s the letter he wrote explaining the union’s intentions. What I’m not clear on is what sparked the union to push for a contract at Infinity: Did teachers ask for this, or was it a separate push by the union?