There have been angry scenes outside Tasmania's Parliament as schoolchildren as young as nine protested against abortion.

More than 200 people rallied against proposed changes to the state's laws to allow abortions up to 24 weeks into a pregnancy.

The crowd included young children - some in school uniform - who held placards and banners, some carried images of the foetus while one read, "face it, abortion kills a person".

Southern Christian College principal Alan Lawson says students and parents want their views on abortion heard.

"This is part of life. We teach kids for life," he said.

"We don't have some academic curriculum that hides itself from the reality of the world in which we live.

"So we see this as real education.

"We're very careful with how we deal with it, but we do feel that we wish to be heard on this issue and we feel that children have a right and wish to be heard on this issue too."

Premier Lara Giddings said the protest was abhorrent.

"I think that people will look at that and think that's a step too far," she said.

"I find it really abhorrent to see the sort of campaign that's been raised now on a really sensitive issue.

"I'm concerned to see young kids involved in a debate like this.

"There was a good point made in some of the commentary that I saw, that these young people are at an age that they haven't actually lived long in the life to experience the competing issues that adults have to confront in their lifetime."