Being from the US provides no additional knowledge of the ACT test, nor an advantage to a 7th grader taking the ACT test; A family being from outside the US does not place a 7th grader at a disadvantage in taking the ACT. The ACT website provides information on the testing process, what to expect, what to bring, what not to bring, etc.
The ACT assesses a large body of knowledge, and is constantly changing and evolving, therefore the content knowledge which it tests for, and the scores which students achieve, vary.
Just as athletes may have career performance statistics and season performance statistics... which may be indicative of overall ability... these may not be predictive of the performance relative to others on a particular day. For example, top athletes favored for Olympic gold may sometimes be outperformed by others on that particular day.
