After Parkland shooting, worldwide 'March for Our Lives'

FILE- This March 14, 2018 file photo shows Students sitting in silence as they rally in front of the White House in Washington. Students walked out of school to protest gun violence in the biggest demonstration yet of the student activism that has emerged in response to last month's massacre of 17 people at Florida's Marjory Stoneman Douglas High School. In the wake of a Valentine's Day shooting, a handful of Parkland, Fla., teenagers are on the cusp of pulling off what could be one of the largest marches in history with nearly 1 million expected in DC and more than 800 sister marches planned across every continent. (AP Photo/Carolyn Kaster, File)
In this, Wednesday, March 14, 2018 photo, Casey Sherman, center, 17, lead student coordinator for the Parkland march, speaks during a planning meeting with Marjory Stoneman Douglas High School students, parents and volunteers in a hotel meeting room in Coral Springs, Fla. The students from Marjory Stoneman Douglas High School have spearheaded what could become one of the largest marches in history. Organizers say they are expecting perhaps 1 million people in the nation’s capital Saturday, March 24. More than 800 sister marches are planned from California to Japan.(AP Photo/Wilfredo Lee)
FILE- This March 14, 2018 file photos shows students at Roosevelt High School taking part in a protest against gun violence in Seattle. In the wake of a Valentine's Day shooting that killed 17, a handful of Parkland, Fla., teenagers are on the cusp of pulling off what could be one of the largest marches in history with nearly 1 million expected in DC and more than 800 sister marches planned across every continent. (AP Photo/Manuel Valdes, File)
In this March 14, 2018 photo, Casey Sherman, center, 17, lead student coordinator for the Parkland, Fla., march, speaks during a planning meeting with Marjory Stoneman Douglas High School students, parents and volunteers in a hotel meeting room in Coral Springs, Fla. The students from Marjory Stoneman Douglas High School have spearheaded what could become one of the largest marches in history. Organizers say they are expecting perhaps 1 million people in the nation’s capital Saturday, March 24. More than 800 sister marches are planned from California to Japan. (AP Photo/Wilfredo Lee)
FILE - In this March 19, 2018, file photo, Marjory Stoneman Douglas High School students Alex Wind and Ryan Deitsch, right, discuss the upcoming marches in Washington and elsewhere. The movement is calling for gun regulations during an interview in New York. In the wake of a Valentine's Day shooting that killed 17, a handful of Parkland teenagers are on the cusp of pulling off what could be one of the largest marches in history with nearly 1 million expected in DC and more than 800 sister marches planned across every continent. (AP Photo/Bebeto Matthews, File)
In this, Wednesday, March 14, 2018 photo, Rabbi Melissa Stollman of congregation Kol Tikvah, offer help for the Parkland, Fla., march, during a planning meeting with Marjory Stoneman Douglas High School students, parents and volunteers in a hotel meeting room in Coral Springs, Fla. The students from Marjory Stoneman Douglas High School have spearheaded what could become one of the largest marches in history. Organizers say they are expecting perhaps 1 million people in the nation’s capital Saturday, March 24. More than 800 sister marches are planned from California to Japan. (AP Photo/Wilfredo Lee)

After Parkland shooting, worldwide 'March for Our Lives'

FILE- This March 14, 2018 file photo shows Students sitting in silence as they rally in front of the White House in Washington. Students walked out of school to protest gun violence in the biggest demonstration yet of the student activism that has emerged in response to last month's massacre of 17 people at Florida's Marjory Stoneman Douglas High School. In the wake of a Valentine's Day shooting, a handful of Parkland, Fla., teenagers are on the cusp of pulling off what could be one of the largest marches in history with nearly 1 million expected in DC and more than 800 sister marches planned across every continent. (AP Photo/Carolyn Kaster, File)
In this, Wednesday, March 14, 2018 photo, Casey Sherman, center, 17, lead student coordinator for the Parkland march, speaks during a planning meeting with Marjory Stoneman Douglas High School students, parents and volunteers in a hotel meeting room in Coral Springs, Fla. The students from Marjory Stoneman Douglas High School have spearheaded what could become one of the largest marches in history. Organizers say they are expecting perhaps 1 million people in the nation’s capital Saturday, March 24. More than 800 sister marches are planned from California to Japan.(AP Photo/Wilfredo Lee)
FILE- This March 14, 2018 file photos shows students at Roosevelt High School taking part in a protest against gun violence in Seattle. In the wake of a Valentine's Day shooting that killed 17, a handful of Parkland, Fla., teenagers are on the cusp of pulling off what could be one of the largest marches in history with nearly 1 million expected in DC and more than 800 sister marches planned across every continent. (AP Photo/Manuel Valdes, File)
In this March 14, 2018 photo, Casey Sherman, center, 17, lead student coordinator for the Parkland, Fla., march, speaks during a planning meeting with Marjory Stoneman Douglas High School students, parents and volunteers in a hotel meeting room in Coral Springs, Fla. The students from Marjory Stoneman Douglas High School have spearheaded what could become one of the largest marches in history. Organizers say they are expecting perhaps 1 million people in the nation’s capital Saturday, March 24. More than 800 sister marches are planned from California to Japan. (AP Photo/Wilfredo Lee)
FILE - In this March 19, 2018, file photo, Marjory Stoneman Douglas High School students Alex Wind and Ryan Deitsch, right, discuss the upcoming marches in Washington and elsewhere. The movement is calling for gun regulations during an interview in New York. In the wake of a Valentine's Day shooting that killed 17, a handful of Parkland teenagers are on the cusp of pulling off what could be one of the largest marches in history with nearly 1 million expected in DC and more than 800 sister marches planned across every continent. (AP Photo/Bebeto Matthews, File)
In this, Wednesday, March 14, 2018 photo, Rabbi Melissa Stollman of congregation Kol Tikvah, offer help for the Parkland, Fla., march, during a planning meeting with Marjory Stoneman Douglas High School students, parents and volunteers in a hotel meeting room in Coral Springs, Fla. The students from Marjory Stoneman Douglas High School have spearheaded what could become one of the largest marches in history. Organizers say they are expecting perhaps 1 million people in the nation’s capital Saturday, March 24. More than 800 sister marches are planned from California to Japan. (AP Photo/Wilfredo Lee)