Every few weeks or months, after a man armed with a high-powered weapon walks into a school or a church or a nightclub and opens fire, the national response plays out in a rote, almost performative way. The outcry lasts only a few days before guns fade back into the background noise of American politics.

But nearly three weeks after a gunman walked into Marjory Stoneman Douglas High School in Parkland, Fla., and killed 17 people with an AR-15, the conversation has not faded, because the students of Stoneman Douglashave taken up the cause of gun control. Already, they have lobbied state lawmakers in Tallahassee, spoken with President Trump and persuaded many companies to cut ties with the National Rifle Association. And on Saturday, they met with students fighting gun violence in Chicago.

Several of those students, and their critics, have noted the incongruity of teenagers getting involved in politics. But history is full of movements led by students — albeit usually in college, not high school. Some were successful and others brutally crushed, but even the latter still resonate. (Most of these campaigns have been liberal-leaning: Though conservative college students have made their presence known, their actions have rarely coalesced into broader movements.)

Here are seven other cases where young people were moved to challenge adult society. ...