PORTLAND — Over the next two weeks, Portland’s school district will install filtering software on laptops issued to high school students, in order to block access to pornography, social networking sites and video streaming sites when the laptops are at home.

Access to those sites is blocked now only at school, through the school network. The current filter doesn’t work when laptops are off school property.

The district will install filtering software made by Sophos, an Internet security company based in Boston. The software will be downloaded automatically when the students boot up their computers at school. Only when students get home will they discover that their lives have changed in a big way.

No longer will they have access to social networking sites like Facebook and video-streaming sites like Hulu and YouTube. Also blocked will be forums and news groups, games, dating sites, gambling sites and chat rooms.

Portland will be among Maine’s first school districts to filter laptop computers used at home to such an extent, said Jeff Mao, learning technology policy director for the Maine Department of Education.

The change means students will use the computers for their intended purpose – as educational tools – not a source of entertainment, said Peter Eglinton, chief operating officer for the district.

“Teachers will be happy with the change,” he said. “Parents will likely be happy. Students will not be.”

Indeed, when told the news last week, several Portland High School students were furious.

Eglinton said teachers will be able to allow access to sites that offer educational videos, such as those offered by Kahn Academy, a nonprofit with an extensive video library of courses.

Portland’s high school students use Dell netbooks provided by the city. School officials plan to install the same filtering software next fall on the Apple MacBooks used by middle school students.

There are legal reasons behind the district’s decision, Eglinton said. Schools that receive discounts for Internet access through federal so-called E-Rate funding are required to take steps like creating an Internet safety policy and filtering and blocking access to certain types of online content.

“To be compliant (with the law), we should be filtering at home,” he said. “Now, we have the software and the ability to do it.”

School officials will notify school employees, students and parents about the changes this week.

A districtwide filtering system can be difficult to manage because there is tension between teachers’ need to have access to the best Internet tools and the capacity of the filtering software to maintain an accurate list of prohibited sites.

There is debate nationally about whether schools should integrate social media in the classrooms, said Rebecca Randall, vice president of education programs for Common Sense Media, based in San Francisco. She said she is not aware of any school district that has blocked access to social media sites from school computers that are used at home.

She said the debate over filtering policies can be summed up into two approaches: the “walled playground” or the “open sandbox.”

Her organization advocates the latter approach, allowing broad access and teaching children how to safely navigate the Internet.

“Simply shielding students from social media is not going to stop them from seeing it,” she said, because teenagers will have access to unfiltered Internet on home computers and other devices, such as smartphones and tablets. “We have a saying: ‘You can’t always cover kids’ eyes. You have to teach them how to see it.’ “

While federal law requires school districts to take measures like creating an Internet safety policy and blocking sexually explicit content, there is no requirement that social media sites be blocked, said Doug Levin, executive director of the State Educational Technology Directors Association, based in Maryland.

He said school districts have a fair degree of discretion regarding which sites to block.

In fact, the U.S. Department of Education recently issued guidelines explaining that it is acceptable to allow social networking sites and video streaming, said Deborah Caldwell-Stone, deputy director of the American Library Association’s Office of Intellectual Freedom.

While there is plenty of discussion about where school districts should draw the line, there is no debate that districts have the right to install filtering software on school equipment, she said.

The Portland school district is doing it without any discussion by the school board. Eglinton said many parents and teachers have told him they want the laptops to be filtered at home. It’s an issue for teachers at Portland High School, he said, because students in certain parts of the building can get open Internet access from nearby businesses.

School board Chairwoman Kate Synder, the mother of a ninth-grader at Portland High, said that as a parent she favors the new restrictions, because they will help students stay focused on their schoolwork.

She said she never wanted her children to have television in their bedrooms. But thanks to streaming sites like Hulu and YouTube, laptop computers also function as television sets.

Snyder said the school district shouldn’t give students equipment that makes it harder for parents to do their job, which is to help children stay focused on academics. She said the district has the right to filter the Internet.

“It’s a school-issued laptop,” she said. “If that’s something that the student wants to do on their own time and on a family computer, that’s OK.”

The change’s impact on students will depend on whether they have access to other computers at home. For many poor families, the school-issued laptop is the only computer in the house.

In interviews with Portland High students last week, those from middle-class families expressed various degrees of annoyance when told of the new filtering measures. A group of immigrant students reacted with anger.

“When we are at home, we need to have something else to look at besides homework,” said Fatush Jama, a senior.

“Where can we go to share if we don’t have Facebook?” asked Nateho Ahmen, a 17-year-old junior. “Who came up with this idea? We are going to have a long talk.”