A Massachusetts school district has apologized to parents after a group of schoolchildren participated in midday Muslim prayers during a field trip to a Boston-area mosque.

The incident occurred in May when a social studies class from Wellesley Middle School toured the Islamic Society of Boston Cultural Center, one of the largest mosques in the Northeast.

Parents were told their children would be learning about the architecture of a mosque and they would be allowed to observe a prayer service. But the students wound up being given a lecture on the Prophet Muhammad, and some boys participated in a midday prayer service.

The field trip was videotaped by a parent whose child was on the trip. At one point, the video shows a spokeswoman for the mosque telling students, “You have to believe in Allah, and Allah is the one God, the only one worthy of worship, all forgiving, all merciful."

Attorney Rob Meltzer represents the parent, who asked not to be identified. He’s launched an investigation into the incident and says he may consider filing a lawsuit or complaint against the school district.

“Personally, I was appalled,” Meltzer told FOX News Radio. “We are obviously very concerned about how much control parents were given and the lack of informed consent.”

The sixth graders were also reportedly told that jihad is a personal spiritual struggle that has nothing to do with holy war, and girls on the field trip were told that Islam is pro-women.

“Islam was actually very advanced in terms of recognizing women’s rights,” an unidentified mosque spokeswoman says in the video. “At the time of the Prophet Muhammad, women were allowed to express their opinions and vote. In this country, women didn’t gain that right until less than a hundred years ago.”

Dennis Hale, a spokesman for Americans for Peace and Tolerance, which has been critical of the mosque, told Fox News Radio that the students were then instructed on how to pray during the midday service.

He said mosque officials separated the group by gender and invited male students to join traditional Muslim prayers. The video shows young boys bowing and prostrating themselves – with their heads touching the floor. At no point during the event did any school teacher or school official intervene.

But the Muslim American Society of Boston told the Boston Globe that no one asked the students to participate in the prayers.

“Certainly in our tours we do not invite kids to take part, but if someone wants to come and pray and take part, we shouldn’t prevent them,” the group's president, Bilal Kaleem, told the newspaper. “It’s more an issue with the school.”

But Hale says the mosque was engaged in proselytizing. “You can easily imagine what would have happened if a Catholic priest had taken some kids from a school to teach them about Catholicism and have them take communion without telling the parents,” he told Fox News Radio. “The furor would be visible from outer space.”

On Thursday, nearly four months after the incident, the Wellesley School District sent a letter to parents apologizing for what happened.

“I extend my sincere apologies for the error that occurred and regret the offense it may have caused,” Superintendent Bella Wong wrote in a statement provided to FOX News Radio. “In the future, teachers will provide more clear guidance to students to better define what is allowed to fulfill the purpose of observation.”

Wong explained the field trip was part of a course titled, “Enduring Beliefs and the World Today.” It included a visit to a synagogue and a mosque – along with a gospel music concert and a meeting with representatives of the Hindu religion.

She acknowledged that five students participated in the midday Muslim prayers, and she confirmed that a parent videotaped the incident.

“It was not the intent for students to be able to participate in any of the religious practices,” she wrote. “The fact that any students were allowed to do so in this case was an error.”