Is the "set" in mathematics the same as that in physical education class? Why?
Same. The word "assembly" first reminds us of all the assemblies that teachers often shout in physical education class or in meetings. Mathematics set has the same meaning as this, except that one is a verb and the other is a noun. So the meaning of a set is that some specified objects are brought together into a set, which is called a set for short, and each object is called an element. For example, the collection of Grade One and Grade Two, then all the students in Grade One and Grade Two form a collection, and each student is called the element of this collection.