Ask some parents and they'll say, 'Stop politicking on school issues.'

The air is electric with anticipation. Cars, empty but for the drivers, line the street and surround the building. Inside, young faces wear a mixture of anxiety and excitement; how will their ''critics'' grade their performance this time?

It's not opening night on Broadway - it's the last day of school here at Hastings Maria Elementary School, where report cards are being handed out.

As parents wait in the line for their children, they are questioned about the national attention being focused on the quality of public school education in the United States, and in particular on the idea of merit pay for teachers.

Although the immediate concern of most is how they're going to keep their children entertained during the hot summer, it is evident that the quality of teaching their children receive is also at the forefront of their concerns.

These and other Boston-area parents interviewed said that the issue was becoming a political football. They added that the discussion over merit pay - awarding higher salaries to teachers judged to be superior - tends to simplify the complicated problems schools face.

''I think the concept of merit pay is good,'' says Sharon Caldwell, shading her eyes against the bright June sun. She is the mother of three children in the Lexington, Mass., school system. ''But how are you going to enforce it? Who decides? It seems to me there will always be some politics there, someone playing favorites.''

''I don't think pay should be singled out as a large issue, there are plenty of things that need just as much attention,'' says Marie Galloway, standing beside her nine-passenger station wagon. She needs all that room, too. Her six children attend the Hastings Maria school.

Pam Northridge, the mother of a first grader, disagrees. ''I think (merit pay) is a good idea, but the schools always seem strapped for money. I don't see how they could do it. I really think they all should get a raise.''

The recent report by the National Commission on Excellence in Education entitled ''A Nation of Risk'' outlined the problems facing America's public schools and touched off debate over what course of action should be taken to reinvigorate education in the United States.

Of all the issues touched on in the commission's report, merit pay especially has caught the fancy of politicians at all levels and has even been swept into the vortex of presidential politicking. President Reagan and Democratic presidential contender Walter Mondale have squared off over the education issue, using merit pay as their weapon.

''There are a lot of issues that we have to be worried about,'' says Judy Murphy, the mother of two school-aged daughters and a resident of Boston's Hyde Park neighborhood. ''We have to be worried about the whole education thing. To me everybody has a role in educating the kids, from the school department down to the kids themselves. Teachers shouldn't be singled out as the most important factor.

''I think there are too many other things to look at before we can start giving teachers merit raises,'' she continues. ''Give the kids the incentives. The kids are bored and that's when the problems get started.''

Merit pay appears to be more of an issue in wealthier school districts. Parents whose children attend run-down inner-city schools tend to view the discussion of merit pay as a luxury issue.

''More to the point, I think, is the number of teachers in school - the teacher-student ratio,'' says Palmer Doiley of the Roxbury section of Boston. He has three children who are going into the 2nd, 6th, and 10th grades in the city's public schools.

''I don't know what we need to pay to have classes of less than 40 students, but whatever it takes, that should be a top priority,'' he says.

Ellen Guiney, a Beacon Hill resident with three children in public schools, says she'd like to see a variation on the merit pay concept: Give a pay raise to all teachers, but keep only the most qualified ones. ''I would like to see all teachers paid more - a lot more - and demand a lot more from them,'' she says.

Back in Lexington, a loud bell marks the end of school - but for the students , it's a starter's pistol. With arms held high in joyful freedom, children burst through the front door of the school, their hands clasping old papers and excess clothing.