A discrepancy between achievement test scores and IQ scores *can* indicate a learning disability. However, because achievement tests are designed to test achievement (in other words, what kids have learned), they will reflect the learning opportunities that a child has had.
If a child has been in a school where they are not accelerated and not being exposed to additional material elsewhere, that child may score only in the average ranges on an achievement test like the WJ, which covers a wide range of grade levels. Most kids who haven't been exposed to material past their current grade levels, can't perform at really high levels.
This is not to say that your child shouldn't have better instruction. I think those scores indicate that pretty clearly!
