In a political climate where most adults are inert with despair, a growing number of teenagers are responding with action. After 14 children and three adults were massacred at Marjory Stoneman Douglas High School in Parkland, Florida, it was students – not parents, teachers or political representatives – who organised themselves to campaign for changes to US gun laws. The March for Our Lives demonstration in Washington, DC on 24 March was accompanied by sister marches around the world: millions of young people supporting each other and demanding policy reform. Lead campaigner Emma González, a high-school student who now has more than 1.5m Twitter followers, made a call to arms for her peers to: “Fight for your lives before it’s someone else’s job.”

González is one of many teenagers shattering the stereotypes of the lazy, entitled, self-obsessed millennial. More and more teenagers are noisily questioning the world they’re inheriting and demanding things work differently. Here, we meet some of the young activists whose voices are increasingly impossible to dismiss.

Amika George, 18, London: Campaigning against period poverty

Last spring, I was watching the news when there was a report on girls in the UK missing school because they couldn’t afford menstrual products. Some were using toilet paper, newspaper or socks. Thinking about girls my age going through this hit me hard. The report gained attention, but I felt the government was sweeping it under the carpet and we needed to pressure them to do something. So I did what felt normal to me and went online and started a petition. It calls for free menstrual products for children on free school meals. I didn’t imagine even getting 100 signatures. But in between revising for AS exams, I emailed as many people, companies and universities as I could. I asked my parents to send it around their work. My dad was a bit reluctant at first, but he did.

There’s huge embarrassment about periods, but it’s something half the world’s population will go through for a week every month. That it’s a taboo holds us back in achieving gender equality. Within two weeks, the petition reached 2,000 signatures. Comments were divided between people being shocked that this happens and others saying it affects them or their friends. Hearing that made me want to fight harder.

When the general election was announced, I emailed the parties. The Green party and Women’s Equality party both replied and included a pledge in their manifesto. I was so frustrated I couldn’t vote. Then in December we organised a protest outside Theresa May’s bedroom; more than 1,000 people came and shouted. To date, 150,000 people have signed the petition. It’s sad when adults are surprised to hear a young person being politically vocal. Young people are angry about the state of the world and a lot of us use social media to articulate that. I get asked to speak a lot.

The other morning, a TV station sent a car to school, I left for an hour, spoke on the issue and came back to a history lesson. My parents are supportive and as surprised as me that this has taken off. My dad went with me to the Women’s March, which was cool. But sometimes my mum can get annoyed if I’m doing lots of campaign stuff with exams coming up.

Xiuhtezcatl Martinez, 17, Colorado: Climate change activist

If someone tells me I should be in school right now, I know that they don’t see the bigger picture. Earth’s ability to support human life is falling apart and if things don’t change in the next five to 10 years, nothing’s going to matter.

I’ll finish high school, but right now this is the most important thing I can do with my time. Myself and 20 other kids are currently suing the Trump administration for violating our constitutional rights for failure to act on climate change. We originally launched it against the Obama administration a few years ago. The US government has known the fossil fuel industry is having a negative impact on our climate, yet they have been offering them subsidies and opening up land to exploration. We have just heard that we are going to trial in October.

I’m also involved in law actions and civil disobedience to stop fracking around my hometown of Boulder. In 2012, my friends and I successfully helped push for a five-year ban.

From a young age, I was aware of my part in protecting our planet. I was three or four the first time I went on a protest, and six when I started speaking at them. I was born in Colorado and have spent a lot of time in Mexico. My entire childhood was travelling, hanging out in nature and learning about my family’s indigenous heritage. My dad taught me that we have a responsibility to protect the Earth the way that our ancestors did.

I’ve spoken at the UN about my work. I was surprised how disrespectful, disconnected and sterile it was. The delegates were on their phones, not listening. They perked up when they heard I was just 15 years old. The power of me speaking wasn’t for them but for the millions of people my speech has since reached online.

The world is seeing how powerful young people are and how things are going to change. Adults on CNN and in the United States specifically, they can argue and cover gossip about Trump and his hair and porn stars. But young people are mobilising on the streets.

There’s so much power in what’s happening within our generation. We don’t have the respect we deserve, but I think it’s coming.

Shiden Tekle, 18, London: Diversity in the media

I’ve been racially abused since about 12, but it was never seen as an important thing to tackle. At secondary school, white children called me disgusting things, but teachers would turn a blind eye. And not just to racism, but sexism, homophobia, transphobia. There’s also internal racism in the Eritrean community. My dad is called names because he has darker skin. It all comes from preconceived ideas that black is less, or the darker you are the lower you are in terms of income, society and politics.

Because these problems weren’t taken seriously, I normalised them. But when I moved to a sixth form where the majority of students are black girls, I was surrounded by political and social consciousness. The more educated I got, the angrier I became. Last summer, I joined an organisation called the Advocacy Academy and, with a small group of people my age, we launched a campaign challenging the image and under-representation of black people in the media. We recreated iconic posters, such as Doctor Who, Titanic and Harry Potter, and made all the characters black. The campaign is rooted in personal experiences and I’ve gone from talking about things with my friends in the lunch hall to speaking about them nationally.

The Academy has revolutionised the way I think. Back in the day I definitely upheld toxic masculine identities. I’d tell myself that I didn’t cry. Challenging gender norms wasn’t of interest to me because I wanted to fit in with my friends. But I’ve learned to let go of my ego and be vulnerable so I can say what’s on my mind. It’s allowed me to take all the cold anger I have built up over years and turn it into something good. I’ve learned to become an ally to many other issues that don’t affect me directly.

After university, I don’t just want to get a really good job, buy a big house and forget about my community. I want to change something and challenge the status quo.

Muzoon Al-Mellehan, 19, Newcastle: Education for refugee children

Even before the war in Syria, I wanted to change society, but I knew I needed to get educated to do that. Back then, we had a normal life. We went to school every day and saw our friends. The war started when I was 11 or 12. Going to school became difficult. There were people fighting on the ground, there would be bombing, sometimes bullets. Sometimes school was just closed because of budgets. My father is a teacher and he lost his job.

We left Syria five years ago, when I was 14. I was so worried about my future and education. We went to a refugee camp in Jordan. I didn’t expect there to be a school, but I was happy to discover a caravan with a tent and some teachers. There was no electricity. We studied computing from a book. In the winter, it got so cold it was hard to focus on the teacher.

But school gave me hope. And I started to encourage other girls and boys to go, too. I would walk from tent to tent, caravan to caravan, persuading kids and parents. I met people who thought that because we are refugees, education isn’t important any more, or that they’d continue school when they returned to Syria. I encouraged people to believe in themselves and not give up. I met kids who’d never been to school, and girls who saw marriage as their profession. Some parents told me it had nothing to do with me. I fought hard for everyone to believe that we can’t do anything without knowledge and got involved with international charities who supported me.

What’s happening in my country is not of our making and it’s not our fault that we’re losing our rights. One day, we’ll be able to return, and we need to have knowledge. After three years in Jordan, my family came to the UK. Last year I became the youngest and first refugee Unicef Goodwill Ambassador. I’m now on my way to university and am doubling my activism.

Ellen Jones, 19, London: Campaigning for LGBTQ+ rights

I came out at 14. When you’re a young LGBTQ+ person and you come out, you’re put in this position where you are suddenly expected to educate your peers. I’d be in a lesson and someone would ask me an incredibly inappropriate question. People feel like they have permission to access all of you when you’re still figuring things out for yourself.

At the same time, someone in my class was sending me online anonymous, violent messages, telling me to kill myself. My school didn’t know what to do with it. At one point, they had contacted my parents, pushing me to come out to them, too, and it all became detrimental to my mental health.

I don’t come from a political family, but I’ve always had a strong sense of fairness. After coming out, I started making educational YouTube videos on LGBTQ+ issues and people watched them. I also worked with my school to establish support systems and visibility for LGBTQ+ pupils. I got together with teachers to set up a group. We held events and assemblies, and suddenly others wanted to join. I worked with the school to run surveys of the staff and students, so we knew the issues that needed addressing.

As part of a Stonewall youth programme, I started a YouTube series called Queeries. I invite anyone to submit questions, however inappropriate or silly, and I sit down with another LGBTQ+ person and we answer them. Part of that is creating space for difficult questions, but also to give others a platform. I am very aware of the fact that I am white, middle-class and able-bodied, and there are a lot of things I feel I can’t speak to. I have been diagnosed with bipolar disorder and autism, but campaigning is always something I’ve felt able to do.

I was happy to do the work with my school, and I know that education resources are stretched, but schools shouldn’t rely on pupils to affect change. That puts pressure on young people to challenge things adults should be addressing.

Many young people think they aren’t going to amount to anything because of all the headlines we read. But that’s designed to discredit our concerns about how the world’s being run. A lot of people in control are invested in the world as it currently stands; to suggest that things aren’t great the way they are scares them.

Emma González, 19, Florida: Gun-control activist

We are going to be the kids you read about in textbooks. Not because we’re going to be another statistic about mass shooting in America, but because we are going to be the last mass shooting. Just like Tinker v Des Moines, we are going to change the law. And it’s going to be due to the tireless effort of the school board, the faculty members, the family members and most of all the students. The students who are dead, the students still in the hospital, the students now suffering PTSD, the students who had panic attacks during the vigil because the helicopters would not leave us alone, hovering over the school for 24 hours a day.

If President Trump wants to tell me to my face that it was a terrible tragedy and how it should never have happened and maintain telling us how nothing is going to be done about it, I’m going to happily ask him how much money he received from the National Rifle Association.

It doesn’t matter because I already know: $30m. And divided by the number of gunshot victims in the United States in the first one and a half months of 2018 alone, that comes out to being $5,800 each. Is that how much these people are worth to you, Trump? If you don’t do anything to prevent this from continuing to occur, that number of gunshot victims will go up and the number that they are worth will go down. And we will be worthless to you.

To every politician who is taking donations from the NRA, shame on you. The people in the government who were voted into power are lying to us. And us kids seem to be the only ones who notice and call BS. Companies trying to make caricatures of the teenagers these days, saying that all we are is self-involved and trend-obsessed and they hush us into submission when our message doesn’t reach the ears of the nation, we are prepared to call BS.

Politicians who sit in their gilded House and Senate seats funded by the NRA telling us nothing could have been done to prevent this, we call BS. They say tougher guns laws do not decrease gun violence. We call BS. They say a good guy with a gun stops a bad guy with a gun. We call BS. They say guns are just tools like knives and are as dangerous as cars. We call BS. They say no laws could have prevented the hundreds of senseless tragedies that have occurred. We call BS. That us kids don’t know what we’re talking about, that we’re too young to understand how the government works. We call BS.

This is an edited transcript from the speech student and activist Emma González gave at the anti-gun rally in Fort Lauderdale on 17 February 2018, three days after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida