My son just completed second grade, so if he scored "proficient" on the third grade test he would have gone straight to fourth.
The school calls it "proficiency based promotion" instead of acceleration.

I did not make my question clear. I understand the difference between percent and percentile, but does the ITBS usually report scores in percent or percentile? I've never seen any results, and I'm not sure if they mean 90% is proficient or 90th percentile is proficient.