It always helps to have at least one emergency strategy for each subject because it is easy to just lose focus or not be interested. It can help by getting you back on track or solve a problem.
16 classes have 25 students each which EQUALS a total of 400 students and 3 classes which each have 100 students each which EQUALS a total of 300 and 1 class has a total of 300 students and the total number of students is 1000