Your child breezes through books normally preferred by kids a few years older. She's a fast learner and the most common word out of her mouth is "Why?" You clearly have a smart kid. Should she take an IQ test?

What does IQ mean?

Dr. Paula Olszewski-Kubilius, incoming president of the National Association for Gifted Children, says the IQ score is one way to measure a child's intelligence, but not the only indicator. (A score of 100 is average. Those with scores of at least 130 are generally considered gifted). The number could even change a few points from one day to the next. She says you may want to have your child tested if his intellectual development is out of sync with other kids his age or if he doesn't seem to be working up to his ability in school. A high IQ score might explain why a student is curious at home but would rather talk in class than listen to his teacher. Test results might explain why your math whiz struggles with reading. The bottom line is an IQ test can potentially answer a lot of unanswered questions.

Should your child be tested?

"The parents have to ask, how are they going to use this information?" Olszewski-Kubilius says. Dr. Linda Kreger Silverman, director of the Gifted Development Center, says IQ scores are essential to have. "I consider it as vital as any other information you have about a child," she says. Children with special needs require a personalized learning plan to maximize their potential, and so do gifted children. Silverman recommends IQ testing for kids who develop intellectually at a faster rate than other children or show other signs of giftedness, like a phenomenal memory. Gifted parents also tend to have gifted children, so testing is a good idea if you were a bright child.

She also suggests testing if your child has a family history of a learning disability or shows subtle signs of one, like squinting in bright light. Some gifted children are called "twice-exceptional" because they also have learning difficulties. "Gifted kids cover up all kids of learning disabilities because of their high intelligence," Silverman notes. It's important to make sure that all of your child's learning needs are addressed.

But for other kids the drawbacks of an IQ test might not justify the benefits, says Dr. Richard Courtright, gifted education specialist at the Duke University Talent Identification Program. If children's scores are higher than expected, parents might give them books and puzzles that are too difficult for them. And when children's scores are lower than parents expect, they might be less likely to nurture learning. IQ testing shouldn't be thought of the be-all and end-all of intelligence indicators. IQ testing is most appropriate, Courtright says, when the results could mean different opportunities for your child, like the chance to attend a school for gifted kids.

When to test?

Many parents think their kids are smart. But if you think your child is especially bright, you're probably correct. "Parents are very good, the research shows, at identifying when they think their child is advanced," Olszewski-Kubilius says.

Dr. Rosina Gallagher, a psychologist and president of Supporting Emotional Needs of the Gifted, says it's best to test kids around kindergarten. Have the assessment done by someone who has worked with children and will tell you more than the IQ score. The number isn't as important as what the test results mean. "I think the purpose of the evaluation should be to really understand how the child learns," Gallagher says, not just their level of intelligence.

Ask what the results show about your child's strengths and weaknesses and how best to address them. A tester might recommend that your child skip a grade in school or take some advanced classes, for example.

Silverman says she doesn't recommend IQ tests for children older than 9. That's because highly gifted kids perform so well that the tests won't completely show their abilities.

A better way to assess older kids is to give them tests that are meant for children in higher grades—which Courtright says gives a more accurate picture anyway.

Some colleges run talent searches aimed at assessing bright kids' abilities by giving them advanced tests. Talent searches run by Duke and Northwestern Universities give middle-schoolers the chance to take the ACT and SAT college entrance exams. Olszewski-Kubilius, director of the Center for Talent Development at Northwestern, says this approach works because older kids have developed aptitudes in specific subjects like math or reading.

How much should you share?

Knowing your child's IQ score might help you, but experts say you shouldn't share it with your child, at least until she's old enough to understand what it does—and doesn't mean. It's better to give your child a general idea of what the test showed. "It helps you understand where you fit in," Silverman says. Talk to her about her way of learning and ability to learn in relation to other kids her age. That will mean more to her than a number.

Kids who know their IQ scores might think they're so smart they don't have to work hard in school—or that there's a limit to how much they can learn. Courtright notes that most people think IQ can't change, while there's always room to improve on a math or history test. "Most people see achievement as an alterable variable," he says. "If you get an IQ score of 112, it becomes an excuse to not even try."

The bottom line is that IQ tests aren't for everyone, and you should use the information gained from the test wisely and thoughtfully. No matter what the result, be supportive of your child's learning needs and she'll go far.