polarbear explains everything very clearly (I did no more than a quiet chuckle...=)).
One of the issues that often comes up between school and private psychoed evals is that private psychs use the DSM (as they must, in order to properly bill insurance for testing), while school-based IEP teams are required to use the federal special education disability categories (unless you are fortunate enough to live in a noncategorical state, like Iowa), which do not -quite- match up to the DSM. In some cases, they are more generous, in others, less. Also, school-based teams are required to consider a number of environmental and historical exclusionary factors, which can further cloud the issue, as some types of disabilities are more conducive to some types of exclusionary factors entering the picture. (E.g., lack of access to good instruction is an exclusionary factor for LD, but some unID'ed LD kids act out so they can get themselves removed from the instructionally-frustrating setting, which means they miss out on instruction. So now it's not clear whether their lack of progress is because staff were unknowingly preventing access to instruction in the course of disciplinary measures, or if the lack of progress is primarily due to an underlying LD.) Anyway, the distinction between DSM disabled and federal special education law disabled is one of the reasons it's important to get ahold of, and read thoroughly, parents' rights with regard to special education, to obtain a really good eval from (if possible) a psych who is familiar with the school system you are working with, and (if necessary) to hire an ed advocate who is not only knowledgeable and skilled about the law, but about your particular school system.
On the Beery, there are various options for administration. There is the original core VMI, which is a fine motor near-point copying task, plus two supplementary subtests, which are supposed to separate the motor and visual contributions. If all three were given, you should have three scores from the Beery. If you only have one, then only the VMI portion was given. That is a unitary score.
Also, in most schools, average is 25-75%ile (middle 50%), or even 16-84%ile (one standard deviation plus/minus). Again, private psychs may use different standards of average. Obviously, these means quite a few kids labeled average are having to work rather hard at meeting curriculum standards (or, conversely, might appear somewhat bright in a conventional classroom).