I think so.
I'm no expert, but DS8 has taken the ITBS. So here's my best effort.
I can tell you that ITBS stands for the Iowa Test of Basic Skills. It is an achievement test, so if your child scores well on it one level above grade level, it will probably indicate to the school that some sort of acceleration or differentiation is in order.
If your child is HG+, ceiling issues may mean that you don't know much more than you would have with an at-level test. It really does test more or less for just a single grade level's worth of material, so there's not a lot of space in there to see what a child can do.
Also, (because a lot of people forget/don't know this), a child can get all the answers right and will still not be in the 100th percentile. That would mean that the child did better than everyone (even herself!) and that's not possible.
Also, if a section of the test is fairly easy, the highest percentile possible might be lower than 99th. If 3% of the kids who normed the test got all of them right, than anyone getting a perfect score is in the 97th percentile. Miss one and the percentile might drop back quite a lot, especially if there aren't many questions on that section. I think that is often misunderstood, and especially if the school doesn't use this kind of test normally, you want to be sure that they know not to just look at the percentiles without the context of the number she got right and wrong. Both matter.
For example, I'm thinking of a situation where the school wants a 90th percentile to advance a grade, but a perfect score in one section is only the 89th percentile. You don't want them to refuse services over that--she can't do better than perfect, you know?
I hope I got that right! HTH!
