AUGUSTA (AP) — Lawmakers are requiring high school students, starting with this year’s freshmen class, to prove they truly understand the subjects they study before they can graduate, but they still haven’t worked out many details teachers need to prepare students.

And legislators offered no clarity Wednesday, taking no action on a bill to delay implementation of the so-called proficiency-based diploma during a committee work session.

A 2012 Maine law says all graduating students, starting with the class of 2021, must show they are proficient in eight content areas, such as U.S. history. Maine is one of a growing number of states — including Vermont, Rhode Island and New Hampshire — that have moved toward awarding high school diplomas based on a student’s mastery of subjects rather than time spent in classrooms.

But Maine never passed any regulations to clarify what’s expected of schools, including what proficiency exactly means. Some districts are moving ahead on their own, without guidance from lawmakers, to get students ready.

Lawmakers may meet again next week to consider delaying the law for a year.

The state’s education department has been working on regulations since late last summer and plans to release a proposal in the coming months. Several education groups support a delay so that school districts will have more time to make changes and inform students and the public once the state finalizes new regulations.

“We simply can’t ask our teachers to adjust on the fly as we muck around with this bill ever year,” said Daniel Allen, an instruction and professional development director for the Maine Education Association, in written testimony. The union represents more than 23,000 Maine teachers and education support professionals.

The state will need to spend a lot of money to implement the requirements and educate the public about what exactly proficiency-based diplomas are, said some members of the Maine Curriculum Leaders’ Association, which hasn’t taken a position on a delay.

But the association has said some of its members worry a delay could undermine the program or create confusion with some parents, students and teachers who already have been told the freshman class will graduate with the diploma.

The delay also got support from The Maine Heritage Policy Center, whose analyst Jacob Posik said the proficiency model does little to make sure all Maine graduates are “proficient” learners.