ST. LOUIS — An Illinois public school that requires students who ride the bus to arrive early for optional religious instruction at a Roman Catholic parish has agreed to discontinue the practice in response to a legal challenge.

For generations, most students at the Teutopolis Grade School in central Illinois have started the day with Catholic Mass or other prayer services at the adjacent St. Francis of Assisi Church. The school building is owned by the Diocese of Springfield, which rents it to the public system.

A lawyer for an unnamed and unspecified number of parents who objected to the arrangement said students not participating in the 8 a.m. daily church classes instead wait in the gym, on the playground or in a computer lab, with varying degrees of structure and supervision, before classes begin at 9 a.m.

Under an out-of-court settlement with the American Civil Liberties Union of Illinois, approved by its board last week, the Teutopolis Unit 50 school district agreed to schedule its buses to arrive 15 minutes before class starting in the fall. The settlement also more clearly stipulates the non-religious community groups such as 4-H can have access to the building for after-school programs.

“When government practices favor one particular religious group, the religious liberty of everyone is diminished,” said Rebecca Glenberg, an ACLU senior staff attorney. “We have reached a resolution that protects students from being stigmatized or excluded simply because their family is not of the majority faith.”

Glenberg said more than one parent complained to her group, but the parties were designated collectively as “Parent Doe” to avoid retaliation. She estimated as many as 20 percent of the school’s 500-plus students opt out of the before-school parochial program.

Superintendent Bill Fritcher said the school district is still trying to work out the details of a new bus schedule, including a possible change to some start times. Kindergarten classes start at 8 a.m. Classes for junior high and high school students start 15 minutes later in a separate building. The ramifications on the parish religion classes also are unclear, he said.