Since we are trying to arrange the classes in a sequence where none repeat, we are going to use a factorial, represented by [tex] n! [/tex], where [tex] n [/tex] is the number of items in the sequence.
Since we have four items in our sequence (four classes), our answer is going to be equal to [tex] 4! [/tex], which is equal to 24, as shown below:
[tex] 4! = 4 \cdot 3 \cdot 2 \cdot 1 = 24 [/tex]
There are 24 different ways.