Some kids will do anything — from bizarre to potentially dangerous — to get a day away from school.

That means parents may have to play detective to determine if their child is faking an illness. Trust is a big issue.

If you think all you need to figure out is when your teen or preteen is heating the thermometer, you're behind the curve. The Internet has spawned wikis and discussion boards where kids share their best tips on faking out parents.

Perusing a few of the sites can give you an idea of why some kids lie: They've got a big test, lag behind on a project or paper, perform poorly in several classes, are being bullied or ostracized, or want to hang out alone with a girlfriend or boyfriend.

If other kids planned school projects as elaborately as they plan sick days, they would have no problems with classes. Chronic fakers often have more troubles than just skipping school.

Some things to watch out for if you think your child is faking it:

Frequency. Be on the alert if your kid tells you she's sick every month or six weeks.

Timing. Look for other patterns. If you have to leave for work before your child catches the bus, do you find you're being called at work or on the way to work about symptoms of sickness? Do you get calls from the school nurse during your child's first-period classes?

Setup. Call the mom of your son's friend if your kid says his friend is sick. Some teens who plan sick days will say their friend has stomach flu or some illness; this sets your child up for catching the fake illness after an incubation period.

Homework. Find out from the teacher if you don't know when that book report is due and you doubt your child's memory.

Temperature. Monitor your child and wait five or 10 minutes before dragging out the thermometer after your child suggests he's uncomfortable. That way any spikes in temperature from hot liquids or warm coins under the tongue can even out. Stay in the room while the thermometer is in the child's mouth. Take your child's temperature again in 15 or 20 minutes without announcing it.

Vomiting. Witness it, to be indelicate. Some kids scour the house for stuff, like condensed vegetable soup, to pour in the commode or even in their room. Some will drink vinegar and milk, eat crackers and create other foul combinations to induce upchucking or will use a finger down the throat.

Medicines. Make sure you have control over the medicine cabinet. Some kids will take what they don't need to feel bad; others will not swallow the pills you're giving them so they can stay alert while you're at work.

A sick day should be designed for rest. If you think you're being tricked, eliminate the joys of home: cable, computer, cell phone and iPod.

Sometimes you've got to be strict to be effective. Remember, your child can read if she can't sleep. If she's sick, she won't want to catch up on MTV videos, cruise the Internet, text-message friends or dance the hours away.