Students in the US will remember victims of gun violence and push for firearms control in another wave of school walkouts.
The latest protests are planned for today, the 19th anniversary of the Columbine High School shooting that left 13 people dead in Littleton, Colorado.
Organisers said more than 2,600 demonstrations were planned, from Maine to Hawaii.
Many students said they would wear orange and leave class at 10am before a moment of silence for victims of Columbine and other shootings.
It follows a surge of youth activism following the February 14 shooting at a high school in Parkland, Florida.
Students near Washington plan to rally for gun control at the Capitol. At Columbine High School, classes are cancelled for a day of service.