As school districts around Massachusetts struggle to balance their budgets, lawmakers are considering changing the state’s formula for funding schools. Gov. Charlie Baker, the Senate and the House have taken different approaches to fixing it. Their bills will get a hearing March 22.

Here are some of the questions lawmakers will grapple with as they weigh the different bills:

How does the state make the formula more equitable? How does it bring it in line with the current costs of education? How does the state pay for the skyrocketing costs of health insurance for teachers? And the rising costs of educating students in special education? How much more money does it cost to provide an adequate education for poor children and students who aren’t fluent in English? How much should the state subsidize schools in wealthy and medium-income communities? How much more money should the state be paying for education?

To understand what will happen next, it’s important to understand what’s happening now.

Here’s our primer on how the state pays for education.

Like many other states, Massachusetts dictates how much each community should spend on schools.

“Education is the only area where the state tells cities and towns how much to spend on a local function,” Jeff Wulfson, deputy commissioner for the Department of Elementary and Secondary Education said. “We don’t tell cities and towns how much to spend on a local fire department or on their public works department.”

That is in part because of the state’s constitution, ratified in 1780.

"[I]t shall be the duty of legislatures and magistrates, in all future periods of this commonwealth, to cherish … the public schools and grammar schools in the towns," the framers wrote.

Two centuries later, parents of schoolchildren in Brockton said the state wasn’t living up to its constitutional obligation. Specifically, they argued the state’s school financing system violated the constitution.

In June 1993, the Massachusetts Supreme Judicial Court decided in McDuffy vs. the Secretary of the Executive Office of Education that the state had a duty to provide an education for all students, no matter where they lived. The court left it to lawmakers and the governor to come up with a new funding system.

Later that same month, the governor signed into law the Education Reform Act, which would increase state aid for schools and included a new formula for funding them.

To devise the formula, superintendents and policymakers added up the cost of all the things they thought went into educating kids. That included class size goals of 22 students for elementary school and 25 students for middle school, as well as the cost of teachers’ salaries and benefits, administration, maintenance, teacher professional development, and books. They called it the “Foundation Budget.”

“The importance of the foundation at the time was that it acknowledged there was a minimum amount of money per pupil amount that every community needed to provide for a basic education,” Tom Scott, the executive director of the Massachusetts Association of School Superintendents, said. “That’s why it’s called the foundation budget. It’s the foundation. It’s the minimal amount.”

The average minimum amount now for a student is $11,448 per year. That formula adds additional aid for districts with high percentages of students who are poor or in special education.

Who pays for that? Part of it comes from taxpayers across the state.

“There is no school district in the Commonwealth whose city or town is paying for the full cost of those schools,” Wulfson said. “The state subsidizes the educational costs of every school district in the state. What varies is the amount that we subsidize it.”

To determine how much a community can afford to pay for schools, the state looks at the income of people living there and property values. For communities with a lot of wealth, the state pays up to 17.5 percent of its basic costs per student. In some poorer cities, the state is paying around 90 percent of those costs.

Even though the state sets a minimum cost for educating kids and helps all districts pay for that, it doesn’t set a maximum. For many districts, $11,448 per student isn’t enough. Some spend more than twice that.

“Certainly many districts voluntarily choose to spend more than that from their local resources,” Wulfson said. “That is one of the proof-points that probably the foundation budget does need to be adjusted when so many people feel it’s inadequate.”