Today we're giving the CAHSEE, the California High School Exit Exam. Your state probably has something similar. Since I work with special ed kids, some of them get to have "accommodations," which means they get to use a calculator, or a CD that reads the questions to them, or some other thing that helps compensate for their processing difficulties without actually changing the test (which would be called a "modification").
The calculator is definitely helpful on the math section, and the CD seems to work well on the English section, but there's one accommodation that isn't offered but I know would be extremely helpful--let them listen to music.
Throughout our own high school days, it was universal parental wisdom that kids would study or work best when free from distraction. "Turn off the TV/stereo, sit still, get your nose in that book and study!" But over the past few decades it has become abundantly clear that many types of ADD/ADHD brains (and maybe many other "non-disabled" teenaged brains) actually NEED external stimulation and/or movement in order to function adequately.
The same applies to some adults but they typically have more freedom to make the adjustments they need for themselves (e.g. doodling during meetings to keep their brain activated, listening to music in their office, taking stretch breaks at their own discretion, choosing careers that let them be active). However, kids are usually scolded or disciplined for employing these types of self-management techniques and consequently, their performance and productivity goes way down.
If you're interested in more information on this subject, or if you're just not yet convinced, please visit the following:
Med Page Today
Fidgeting Helps ADHD People Stay Focused
There are countless other articles and studies on this topic as well, which are easily found through a web search.