When Mount Sinai school board members proposed full-day kindergarten, they didn’t expect 160 students to enroll.

But the new program brought an enrollment increase of more than 40 percent, according to numbers the Mount Sinai Board of Education examined during a recent meeting, leading the district to hire another teacher.

By the end of the 2014-15 academic year, which had half-day kindergarten, there were around 112 students enrolled. With the 2015-16 enrollment, Mount Sinai had to bump up the number of teachers to seven.

In May, the board estimated that 125 students would enroll in the full-day program, but by mid-July, there were 151 students.

“All year long … we promoted full-day K at a number around 125 and [aid Mount Sinai received from the state] was based on that number,” Superintendent Gordon Brosdal said. The increase “was a little bit alarming to the board and myself.”

Brosdal said the new program could be popular because full-day kindergarten is easier for a parent’s schedule. He expects several more children to enroll before class starts on Sept. 8, pushing kindergarten enrollment past 160 students.

According to Linda Jenson, assistant superintendent for business, the extra teacher the district had to hire added $85,000 to the budget, bringing the total program cost to $635,000.

Despite that increase, residents will not see taxes go up, Jenson said. Officials dug up the extra money from within the approved $56.7 million budget for 2015-16.

Mount Sinai lengthened the kindergarten day to give young students more time to learn subjects like language arts, math, social studies, science and music.

“We wanted to give our kids and our teachers adequate time to address Common Core, the demands of the curriculum,” Brosdal said.

In half-day kindergarten, students were in school from 8:55 a.m. until 11:05 a.m. With the full-day program, they will stay in the classrooms until 2:58 p.m.