Climate protest: A very different kind of school trip
"Global warming is not cool, that is why we're out of school," chant the enthusiastic primary school pupils as they stand in the shadow of Parliament.
"We are beyond excitement!" says Sue Harte, head teacher of John Stainer Community Primary School in Brockley, south-east London.
She agreed to send 16 members of the School Council to the protest as a kind of educational school trip.
Permissions slips have been returned and parents have signed up to help, but this is a very different kind of trip.
In the end the school delegation is about 150-strong and they are impassioned and in good voice.
Not only does Ms Harte believe climate change is a massive issue, she also wants young people to know about their democratic right of protest.
This comes under the British Values curriculum in England's schools and is a valid use of school time, she says.
As the gathering of red-jumpered juniors get to yell out their well-thought-out chants, other groups of schoolchildren proceed past, swapping energy and chants.
It's getting louder and louder as more and more groups funnel towards the rally in Millbank, and the shrill cries of "climate justice" echo out with an energy that only very young children can muster.
These are nine- and 10-year-olds. and they're fired up and pretty angry - but terribly well-behaved.
It's as if they're finally being allowed to use their outside voices for something they really care about.
One pupil, Lola, who has come with her dad to support the school's official delegation, says: "I came of my own accord. It's so important that we stop the destruction of our planet."
'Nothing being done'
Clutching a small symbolic white toy rabbit, she adds: "We need to think about all the animals we are killing. It's not just humans, it's the animals' habitats - we are destroying their homes."
Heather has brought along her three-year-old daughter Polly, and her one-year-old baby son who is strapped to her chest. He shakes the rattle occasionally in time with the chanting.
"I've come because nothing is being done... Targets are being set but it's not a priority," she says.
"I don't want to have to say to my children that I stayed home and didn't do anything. This is really important," she adds.
Dominic, Lola's dad, who comes from a long line of activists, says: "When you talk and people don't listen, sometimes you have to scream."
There's no doubt that these youngsters are learning about how to protest, but many of them are asking one question: "Will the government listen to us?"