After elementary school, you go to middle school and that takes place for 2-3 years, 6th grade/7th grade through 8th grade. Middle school allows the chance for accelerated classes, and you can skip levels of math in them as well, like taking Algebra when in 6th,7th,8th grade. High school allows you to take larger amounts of varying classes too. All sorts of science classes like chemistry, physics, biology can be taken as a 9th grader.