Tennessee students will have to take a whole semester of state history after all — but no one knows in what grade.

In the waning hours of the legislative session, the House this week approved the change, only days after its sponsor had said he was going to wait until 2018 to hash out the details. The Senate already had passed the measure, which does not specify the grade level for the course.

Now, the state will have to adjust social studies standards that already have gone through a significant amount of review and are one vote from final approval by the State Board of Education. It’s uncertain what that will entail, but board leaders pledged their cooperation.

“The State Board of Education will partner with the Department of Education to ensure that the social studies standards are in full compliance with any new state law before they are heard on final reading at the Board’s July 2017 meeting,” said executive director Sara Heyburn Morrison in a statement.

The law will go into effect for the 2018-19 school year, the year before the new standards, which were supposedly finished, are scheduled to reach classrooms.

One of the reasons for the state’s social studies review, which began in January 2016, was the large number of standards that teachers were struggling to cover. The review panel worked to winnow those down to a more manageable amount and did not include a separate semester for Tennessee history.

To eke the bill through, House leaders amended another bill to include the mandate. Rep. Art Swann, the House sponsor, said Thursday that he was glad not to put off the measure until next year.

“We’re still going to have to wait for implementation, which will take a year or two to get done,”  said the Maryville Republican.

Swann said he didn’t discuss the changes with the State Department of Education. “The Senate sent me the language, and it was fine with me and that’s what we ran with,” he said.

Eight of the nine members of the Standards Recommendation Committee who vetted the proposed new standards believe they allow teachers to go in-depth on important historical topics. But member Bill Carey, who sells Tennessee history materials through his nonprofit Tennessee History for Kids, voted against some of the standards. He was mostly concerned with the reduction of Tennessee historical facts in grades 1-5.

Architects of the new standards say teachers still could cover such topics, but that decisions about how should be made at the local level.

Called the Douglas Henry History Act, the legislation mandating the course is named after the longtime state senator from Nashville who died in March.