As millions of Florida's school children returned to classes this week, many schools struggled to find enough teachers greet and teach them.

"We are very concerned about the growing teacher shortage," Cathy Boehme of the Florida Education Association told the state Board of Education on Wednesday.

Her review of three years' worth of statewide teacher job vacancies posted to district websites in the days before school began revealed a disturbing trend.

Two years ago, Boehme said, the number of advertised teaching positions was about 2,400. Last year, the number rose to 3,000.

This year, it reached 4,063.

"That's the acceleration in the teacher shortage you need to be looking at," Boehme told the board. "This is a critical problem we must address."

Related: With the first day of school around the corner, Hillsborough struggles to fill many teaching jobs

Sumter County schools superintendent Richard Shirley, who's also president of the Florida Association of District School Superintendents, made a similar observation. He noted that it's particularly difficult to find educators in career and technical fields, as well as some science and math disciplines.

"The place we want to go is not just college, but career and life. There's going to be a great demand," Shirley said. "It's hard to get people to come teach in the medical field … because of the salary issues."

He mentioned that Florida's colleges of education have seen decreasing numbers of graduates. With the change in job demands on teachers, some educators are telling their students not to consider the profession.

Districts also have lost some otherwise qualified educators because they could not pass the state's general knowledge exam, sometimes in subject areas they did not teach.

School boards across Florida have heard the concerns with increasing intensity in recent months, as teachers have talked about leaving their districts, the state or even the profession to seek a more livable wage.

In Pasco County, for instance, teachers told their School Board of colleagues working extra jobs to make ends meet. Some schools lost educators through the summer.

The district reported 88 vacancies the week before school began, down to 66 on the first day of classes. (That compared to 89 openings on the first day of 2017-18, 144 in 2016-17, and 440 the year before that.)

Related: Pasco teachers, support staff ask for more competitive pay

State Board members declared that improved teacher salaries would be at the top of their priority list, along with campus security, as they prepare their legislative budget request for the coming year.

"As we approach our legislative recommendation, personally I'd like to see teacher salary adjustments," board member Michael Olenick said, asking for ideas on how to achieve that goal.

Shirley said his district is exploring the creation of a teaching career academy, to prepare high school students who aspire to the profession. He suggested the board call for weighted funding for such a program.

"We have an important workforce need, just like our business partners do," he said.

Education Commissioner Pam Stewart noted that the state has made such recommendations in the past. Two years ago, she said, the department called for $400 million to implement some specific plans aimed at reducing the teaching shortage, including career academies for teaching.

"They didn't ever make it through," Stewart added, holding out the possibility of resurrecting the proposals.

Olenick suggested the state's education-focused associations could work with the department to seek ideas for funding pay hikes. Board member Gary Chartrand put forth that an independent outside group, such as Florida TaxWatch, might lend some objectivity to the discussion, because unlike the others it would not stand to benefit financially from the outcome.

But Chartrand, too, agreed that the state needs to find some way to make it more attractive to teach here.

"I think the teacher shortage is real, and it's going to get worse," he said. "We should get ahead of it."

He advanced the idea of a special scholarship for aspiring teachers as one possibility, adding there could be "a lot of ways to solve this problem. But I do think it's a real problem."

Board members agreed to continue the conversation in September.