She is almost 11 and a 5th grader.
My dds took the ITBS in 1st and 3rd grade at a charter they were attending that time. My oldest, who is also not a fast person (42nd percentile on the WISC as compared to 90s on all of the other indices), did poorly in the fall and really well in the spring. The difference was anxiety.
In the fall, her teacher stressed how important it was which left her so stressed that she came home at the end of the day physically shaking. She didn't finish so much of it that the report said that it couldn't give a core or composite score. In the spring, we convinced her that it didn't matter at all and she scored in the 99th percentile on the totals for reading, language, science, social studies, sources of info, core, and composite. She was in the 92nd for math.
This seemed like an accurate representation of her achievement at that time so my take was that it could be completed in the time gived even by a child whose strength is not speed unless there was a lot of stress or pressure involved. I'm sure that I won't stress my df's child, but I would rather go with the SAT10 if it is likely to work better for her in terms of time constraints, etc.
