The current class in view can be found at the locations indicated below. As you can see this particular class is Monday Period 3 Year 10 English 

The darkened rectangle area within the list (lower arrow), also shows the class currently in view and informs you that there are 33  students in this class.

To change the class currently being viewed, choose another period on this list.

By default when you log into MINTclass you will be taken to your current or next timetabled lesson.