LYNN – About 300 teens will sacrifice food and technology for service and prayer this weekend as part of St. Mary’s sixth annual Hunger for Justice retreat.”It’s the sixth annual hosted by St. Mary’s, but we’ve been doing it for 19 years,” said Andrea Alberti, St. Mary’s School campus minister.Alberti – along with teacher Chris Carmody and with help from nurse Lisa Morin-Plante, Pat Gill, executive assistant to the head of school, and religion teacher Michael McDuffee – coordinates the event that she said never fails to inspire her.The weekend retreat, which includes students from other North Shore schools and parishes, starts today, Good Friday, at noon when St. Mary’s students carry a cross up Nahant’s Short Beach to St. Thomas Church. It will conclude Saturday night with an Easter Vigil Mass at St. Mary’s Church.For the hours in between, the kids give up their cellphones, iPads and all technology as well as food and instead spend their time praying and performing a variety of Christian service projects and outreach.Alberti said she believes the teens have a natural desire to serve and they want to help when they realize that at every second of every day someone dies of hunger.Following a prayer service on Short Beach led by Rev. Matt Williams, Archdiocese of Boston director of faith formation of youth and young adults, the teens will carry a cross to St. Thomas Church, reciting the rosary along the way. They will then participate in a Good Friday service.After the service, the students head to St. Mary’s for their version of the Last Supper – their last meal for more than 24 hours, Alberti said.The kids then participate in various games, prayers and team-building activities, watch “The Passion of the Christ” and make cardboard “homes” to sleep in order to relate to the plight of the homeless.Saturday morning the students will share their feelings when they head to Boston to give away food and toiletries to homeless individuals.”This is a lesson in human dignity, that everyone has value,” Alberti said. “It’s about engaging in conversation.”St. Mary’s collected the more than 1,000 toiletry items to be handed out during Catholic Schools Week in February and Marion Division students got involved by making hundreds of sandwiches, Alberti said.After returning to Lynn, the youth participate in a variety of Christian service projects at homeless shelters, churches and nonprofit organizations. At 5 p.m., the visiting students return to their parishes. St. Mary’s students will then participate in an ecumenical service on Lynn Common then attend the Easter Vigil at St. Mary’s Church, which is followed by a resurrection party, where they get to eat for the first time in 24 hours, including items they gave up for Lent.The Hunger for Justice program has raised more than $125,000 over the last five years and delivered thousands of hours in community service, and Alberti said there are always beautiful moments attached.There was the student who one year gave his socks to a homeless man and teens who gave the shirts off their backs, literally.”I’m absolutely, completely inspired,” she said. “There are these beautiful interactive moments. Heroically beautiful.”