Tearfund has been praising the action of what's expected to be thousands of youngsters, as the education secretary urged students not to miss lessons.
Ben Niblett, who co-leads advocacy at the Christian charity, told Premier: "Climate change is so urgent.
"If our young people are giving us a wake-up call to something we - as adults - haven't really realised the urgency of, then that's really useful and we welcome that today.
"If school children can safely go to an event near them today as a one-off, then we're excited they're doing it and we hope the message gets across."
Organisers of the Youth Strike 4 Climate movement say strikes are taking place across 60 cities and towns.
Inspired by a teenager who regularly protests outside Sweden's parliament building, the group warned of an "alarming lack" of leadership by the UK Government on climate change.
Education Minister Damian Hinds warned the demonstrations would only increase workloads for teachers.
He said: "I want young people to be engaged in key issues affecting them and involving themselves in causes they care about.
"But let me be clear, missing class won't do a thing to help the environment; all they will do is create extra work for teachers."
Meanwhile, Christian Aid said the voices of the striking school children "must be heard".
Youth and campaigns manager, Richard Baker said: "It's understandable that children are angry about the state of the climate their forebears are leaving them. It's a bitter inheritance.
"The fact so many of them feel the need to take this drastic action is a damning indictment of our political leaders."
The strikes follow a UN report which said global temperature rises of more than 1.5C above pre-industrial levels could result in increasingly severe climate impacts.
In November, a climate change protest was staged outside Downing Street by a group of Christians.
Click here to listen to Premier's Alex Williams speaking with Ben Niblett:
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