Some Florida teachers are challenging the state's expansion of the private school voucher program.

The state's main teachers union has filed a lawsuit to block the expansion. In the lawsuit, the union argues that state lawmakers violated a requirment that bills cover only one subject.

The Republican-controlled Legislature attached an unrelated bill on the final day of the 2014 session. They did so because a stand-alone bill failed to get enough votes.

The $300-million program currently in place served nearly 60,000 families this past year. The new law broadens the eligibility for receiving vouchers.