Last year, my child's school selected my child for Gifted testing.
He was not selected.
He will be retested this year.
Is there anything I can do to prep him for this test?
An IQ test is not something you are supposed to be able to study for.
The best things you can do to prepare your child for an IQ test are to make sure that he is well-rested and comfortable during the test. Try to avoid projecting any cause for him to feel nervous about the test itself.
The National Association for Gifted Children has some good information for parents looking to have their children tested for Gifted programs.
In particular, this is relevant information you should keep in mind:
No IQ score should be considered an exact measure of intellectual ability. For example, good guesses may artificially increase an IQ estimate or having a bad day may decrease the estimate. There are many factors that might make an individual score vary a little from one occasion to another on any test. These include anxiety, motivation, rapport with the examiner, and guessing.
So try to make your child as calm and comfortable with the idea of being tested as possible.
My view of the situation is this:
On the strength of an IQ test, your child may or may not be able to take a foreign language program at an early age.
Now, lets make a number of assumptions:
Ok, so all tests, to some degree, can be gamed. Lets say that there was a book out there containing past IQ tests, so that you could familiarise your child with what to expect. If you prep your child in such a way, it may well raise their result in the IQ test, but what effect would it have on their ability to learn the foreign language?
All that would happen, is that your child would start a course that they weren't really ready for. Consequently they will find it too difficult, assuming the logic for applying the IQ test in the first place was sound.
Now, there may well be exceptions to this. For instance, your child may very well know the foreign language already, and may be prevented from studying it early by bureaucracy. IE, the school says that all pupils must have a high IQ in order to study the language. If this is the case I can 100% sympathise. But if your's is just a regular kid (and there's nothing wrong with that) then just let them learn at a regular rate. If you push them too hard they will eventually push back. Remember Newton's Third Law!
On a final note, I am not saying one should never prep for an exam by looking at past papers etc. Far from it, once you have studied the course, you should do all that you can to legitimately gain an edge.