This is an area of apparent disagreement amongst psychologists, or is it? There is agreement that IQ testing is highly predictive of academic potential. In other words it is very good at finding children who have the potential to succeed academically. This doesn't mean that those who do not score well don't ever succeed academically but it would be statistically rare. It most certainly doesn't mean that a child will become successful academically merely because they have the potential to do so. Factors such as tenacity and opportunity come into play, amongst many others.
An IQ test can be very useful in picking up on a child's preferred learning style. For example, they may be far more practically inclined than verbally? This can be very helpful when deciding upon occupational and qualification pathways.
They can be useful when faced with a child who has an apparent learning difficulty; is the child bright in some tasks or delayed in all areas tested?
Children with speech and language difficulties can be identified by the discrepancy between practical tasks and verbal tasks. This is very useful information for speech and langauge therapists.
Some people just like to know their IQ it can add to self esteem.
Knowledge of a child's IQ can be useful evidence if the child fails to thrive in an educational setting, and as such can be a useful precaution. As parents are aware of what should be achieved they can monitor to make sure that achievement levels are being reached and investigate early if this is not the case