When Laurie Tucker’s family moved during her son’s senior year of high school, she was sorry to hear the last two classes he needed weren’t offered at his new school during spring semester. Instead of graduating, he has to finish up in summer school.

An even worse surprise: The family will have to pay for those classes.

On Thursday, students sued the suburban Maryland school system where Tucker’s son attends class in a bid to lift summer-school fees.

Students shouldn’t be able to graduate only if they can afford to, said Tucker, whose son is one of the plaintiffs arguing the right to a free public education is guaranteed under the Maryland Constitution.

Tucker was shocked by the price for summer school in Prince George’s County: $225 per class, which will be a burden for her family. Her husband works as a driver delivering donations to nonprofit agencies, she said, to support their three children; she stopped working two years ago to care for their youngest child, who is 4 years old and has a disability.

Prince George’s schools spokeswoman Raven Hill said it is policy to not comment on pending litigation. But she confirmed the fees: $100 per half credit, with a $25 registration fee, for county students. Those who qualify for free- or reduced-price meals because of their families’ income levels are required to pay only half of those amounts.

Students from outside the county are charged more, $645 for a full credit plus the $25 registration fee. Hill said the fees are mainly to cover the cost of paying employees who don’t normally work over the summer.

Alvin Thornton, chairman of the Prince George’s school board, had not read the case Thursday so declined to discuss particulars. But he said the issue of economic status affecting students’ access to education is important, and he is eager to discuss ways to remove barriers. “That has been a major concern of mine,” he said.

Thornton said he wishes Prince George’s hadn’t been selected as the test case, because it is hardly alone in Maryland in asking students to pay for summer classes.

But a number of counties in Maryland — including Baltimore County — provide summer school free of charge for all students, said Ajmel Quereshi, director of the Human and Civil Rights Clinic at Howard University School of Law. And several counties waive fees for students from low-income families, including Montgomery County.

The ACLU of Maryland and Howard’s clinic in October argued against the Prince George’s policy, which was more stringent in the past, with students charged up to $455 per course, he said. Because the county continues to require payment for summer classes, they sued.

The ACLU, the Howard civil rights clinic, and Cohen Milstein Sellers & Toll are supporting the case, filed in Prince George’s County Circuit Court.

The policy affects thousands of children, Quereshi said; 2,870 students enrolled in summer school in 2016. And the system includes many families for whom class fees could be a burden; about 80,000 students qualified for free or reduced-price meals because of their family’s income level.

Shirley Hill was at one of her sons’ schools Thursday signing him up for biology, math and English classes, and trying to figure out how they would pay.

“There are some parents that can’t afford it,” she said, “And I’m one of them." She works as a caretaker for senior citizens. She said there were about 10 parents in the school office Thursday morning. “It was like a ball of fire in that office this morning,” she said. “People are very, very, very upset.”