at S3 or 3rd year as its called
In Middle School you can pick 1 or 2 electives same as high school. And in college you pick your own classes.
what high school classes should be taken in high school to be a RN
High school level classes to prepare for college
No
That depends on the high school.
It depends on what high school you go to. Different schools have different language classes.
No high school classes, other then your core classes (math, reading, etc.) are required for a profession after high school
Classes that veterinarians take in high school would be biology (other sciences) and math
Your High School classes only have a value in gaining you admission to a college.
The ages, the types of classes, and how many classes
Middle school classes tend to have more responsibility (including homework) than elementary schools, but not quite as much as most high school classes. Also, in many middle schools, extra classes like band are offered.
Take the classes that you are good in and that inspire you/interest you. In college, you can have a major and a minor, usually, so you can pick two fields then.