The incoming 7th grade class has a choice of FRENCH or SPANISH as a language elective. There are 3 times as many Spanish classes as French classes (or 3 to 1). How many students can choose Spanish if there are 850 students? Round to the nearest whole number.
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Since there are 3 times as many Spanish classes as French classes, this means that for every one French class, there will be 3 Spanish classes.
If there are 850 students in total, then we can divide this number by the total number of classes to find the number of students per class.
Since there are 4 classes in total (1 French class + 3 Spanish classes), we can divide 850 by 4 to find the number of students per class.
850/4 = <<850/4=212.5>>212.5
Since we cannot have half a student, we round this down to the nearest whole number, which is 212.
Since there are 3 Spanish classes, this means that there are 3 times as many students in Spanish as in French.
So, there are 3 * 212 = <<3*212=636>>636 students in Spanish classes. Answer: \boxed{636}.