Lots of teenagers are walking together this week in Hillsborough County, a practice they’ve grown accustomed to during this remarkable school year.We can only hope they keep walking for the rest of their lives.Tens of thousands of them this week are wearing the shiny gowns and mortar boards of commencement exercises.Earlier, they marched by the dozens and even hundreds to show their support for a cause. First, in November, it was pay increases pay for their teachers in the Hillsborough County school district, and later, in February, an end to gun violence in the wake of the Marjory Stoneman Douglas High School massacre.Student activism among the Class of 2018 may be more a defining quality to outside observers than it is to the students themselves. After all, only a fraction of them took part and they’re otherwise immersed in the many challenges that confront all seniors on the threshold of adulthood in this day and age.RELATED COVERAGE Parkland turned students into activists. Will it last? Spend any time listening to teenagers about their concerns and you’ll hear about the tension between the home life they have known — often marked by struggles with money, health and relationships — and the future that it’s time for them to pursue.They’re deciding next steps as they hear that college with the advantages it bestows may not welcome them as it once did, that they can expect crippling debt if it does, and that they’re stepping into a world where the rich grow richer and the poor ever poorer.Still, Hillsborough teenagers are showing they can transcend these consuming concerns and view themselves as agents of change for their communities.Bright-eyed idealism, of course, is a hallmark of every graduating class, and a theme in commencement speeches this week. But this group already has shown the capacity to translate idealism into action, to surprise the critics who see only a coddled generation focused on nothing so much as a social media screen.The evidence of this extends far beyond the widely reported marches this year. Scan through resumes from the Class of 2018 and you’ll find them bursting with examples of volunteerism — tutoring fellow students, comforting older hospital patients, teaching Sunday school, assembling care packages for victims of human trafficking.The marches add a new dimension to this selfless behavior. School leaders intervened to create acceptable paths for some of the protests, but student participants still showed their willingness to risk the academic and disciplinary consequences of leaving class to speak for a cause they consider important. As the school year progressed, and anti-gun violence sentiment grew, students everywhere in Hillsborough turned their attention to the issue. In discussions on campus and social media, students took on topics such as how the Supreme Court’s decision in the 2008 Heller decision changes the regulation of gun sales and why the killers and not the victims draw the bulk of the media attention after a mass shooting.And it was a handful of Hillsborough students who took the lead in wider community gun-violence protests that drew some 15,000 participants across three Tampa Bay area counties. Some of them spoke later to an audience of influential adults in Tampa, alternately scolding those who have failed to deal successfully with gun violence and pledging finally — even as the seniors among them move forward in their lives — to be the ones who do.Said one, "This time it will be different."The issues that demand the attention of an engaged citizenry will be different, too, and numerous, once the Class of 2018 walks off the stage with diplomas in hand.Its members are off to a good start in tackling them.