American students planning on participating in this Friday's school climate strike should know their rights in case they're threatened with punishment.

That's the message from the American Civil Liberties Union (ACLU), which reminded students of their rights Thursday by linking to a comprehensive overview of Constitutional protections on school grounds the group created last year. 

"If you're a public school student, you don't check your constitutional rights at the schoolhouse doors," the ACLU document says. "But whether schools can punish you for speaking out depends on when, where, and how you decide to express yourself."

While students might face some school punishment for taking part in the strike, the ACLU notes that the punishment cannot exceed that of similar actions. 

"Because the law in most places requires students to go to school, schools can discipline you for missing class," according to the ACLU. "But what they can’t do is discipline you more harshly because of the political nature of or the message behind your action."

Amnesty International also supports the strike, the organization said in a statement, calling the strike "an important social justice movement that is mobilizing thousands of people to peacefully call on governments to stop climate change."

"It is unfortunate that children have to sacrifice days of learning in school to demand that adults do the right thing," said Kumi Naidoo, secretary general for the organization. "However, they know the consequences of the current shameful inaction both for themselves and future generations."

"This should be a moment for stark self-reflection by our political class," added Naidoo.

Friday's climate strike is a global affair, with students from 112 countries expected to join in a growing movement. In a tweet, teen activist Greta Thunberg said that the strike would take place in 1,769 places across the world. 

"Everyone is welcome," said Thunberg. "Everyone is needed."

On Tuesday, Common Dreams published a comprehensive overview of the climate strike and how to get involved.

Read it here.