Scene One: It's the first time your teenager has faced a serious State exam and tension is mounting. Yours. The "mocks" are about to start, and he spends more time checking the TV listings than he does hitting the books.

You map out study plans for him. "This is important," you suggest, warning him that his school mightn't let him do honours maths or English if he fails them in the Junior Cert, and then he won't be able to get enough points in the Leaving to do rocket science even if he does wise up and start to study, and then he'll face a future living in a cardboard box . . .

Does he listen? Ha.

Scene Two: It's your second Junior Cert. The mocks are about to start and your daughter is having a nervous breakdown. She's studying three and more hours a night, can't sleep properly, bursts into tears or flies into a temper at the least provocation, and has given up watching TV.

"It isn't important," you suggest, reminding her that the Junior Cert is just a rehearsal for the real thing, of course she won't fail and even if she does she won't end up living in a dumpster.

Does she listen? You guessed it.

Little more than a decade ago, the old Inter Cert exam had real significance. Many children left school after taking it, many even found work with it.

The Junior Cert exams don't carry that weight. Only one thing about them is certain: whether your teenager performs good, bad, or indifferent, he or she will be moving on to Transition Year or fifth year next September.

That doesn't mean the exam is unimportant. It may determine whether students will go on to study various subjects at honours or pass level, with obvious implications for the points they can get in the Leaving and the third-level courses open to them. It is also an excellent rehearsal for The Real Thing, whereby a student can find out what a State exam looks like and learn something about how to (and how not to) study, how to (and how not to) pass an exam.

It also gives first-time Junior Cert parents the opportunity to find out how they perform under exam pressure - whether their child is the over-conscientious type who needs to be talked down every night from pre-exam stress, or the laid-back type who needs to be psyched up.

Margaret, a mother of four, has learned a lot about all this in the four years since her eldest did the Junior Cert. Since then, she's had a Leaving Cert and another Junior Cert in the same year; her youngest child will do her Junior Cert exam next year.

She put a lot of pressure on her eldest daughter to do well in the Junior Cert, but is sure she wouldn't worry about it so much now.

"I do think it's significant, that it's a yardstick of how they'll do in the Leaving Cert, an excellent rehearsal that gets them into the way of studying. I would never say to the children that it's not important - but I'd tell other parents not to get stressed themselves. They can save getting stressed for the Leaving Cert."

Her youngest child, like her eldest, has poor concentration. Nonetheless, her eldest teenager did well in the Leaving Cert when push came to shove. Margaret says a child's own personality will determine how he or she tackles a challenge like the Junior Cert; while you can make children go up to their room to work, you can't make them study.

Breda Coyle, a guidance counsellor who is on the executive of the Institute of Guidance Counsellors, says the Junior Cert exams are significant for students in a number of ways - particularly in that determination of who takes honours classes. She cites another crucial issue that may arise: in the months leading up to the exam, students might plead to drop from honours to pass levels in some subjects. "In our school, students have to talk to the guidance counsellor and get a letter from the counsellor saying that they understand the implications of what they're doing - for there are long-term implications of doing this."

Some schools aren't flexible about letting a student go back into an honours class after a change of mind a year later, she warns. She advises parents to go and talk to the school guidance counsellor if their child wants to make this kind of decision.

However, guidance counsellor Vivian Cassells - one of the advisers on the Irish Times "College Choice" helpline - says most schools have an open mind when students start fifth year: if a student who has done badly at Junior Cert level genuinely wants to study all-important subjects like English, Irish and maths at honours level, he believes most schools will try to accommodate them.

But this doesn't mean he thinks the Junior Cert is unimportant. "The exam is useful, as it's the first time somebody outside the school judges a child's performance. And it is a great indicator of Leaving Cert subjects. Students should use it as a way of getting organised, making sure they learn good study habits and exam techniques that will stay with them through to third level." Students should probably be averaging two to two-and-a-half hours study a night, he suggests - picking one or two subjects to do in depth on top of homework.

He also warns: "It's too early for parents to put serious pressure on a young person. If parents put too much emphasis on this exam, when the child gets into fifth year and there's no exam, he or she will just relax completely."