Free IQ tests for children are not easy to find, but they do exist. These free tests are generally not as comprehensive as a test requiring payment, but they can give you a general idea of where your child's intelligence lies.
All The Tests
The site contains more than 80 IQ tests, most aimed at adults. However, if you search through, you'll find several targeted at children. The site links to some for every age range from toddler to teen. Some links lead to external sites, but all are free.
Athey Educational Verbal Reasoning Test
This verbal reasoning test is targeted for children ages nine to 12. It contains 25 questions and is a quick way to get an idea of where your child's verbal IQ is compared to others his age.
Free Online IQ Test
This test, offered in five languages, is available for children and adults. Type your child's age into the box provided to receive accurate results. Not suitable for younger children who won't be able to understand instructions.