The day begins at 7:30 a.m. with breakfast in the Great Hall. During breakfast, the mail arrives in a flurry of hundreds of owls. A bell chime signals the start of the first class at 9 a.m. The bell chimes again in one hour to signal the start of the next class.
There is a break between this class and the following class, making for three classes and a break before lunch. After lunch there is another break and two more periods. You can see also Hermione's schedule in her sixth year: Breakfast in the Great Hall ; Ancient Runes (free period for Harry and Ron) ; Defence Against the Dark Arts ;; Break ;; Arithmancy (free period for Harry and Ron) ;; Lunch in the Great Hall;; Break ; Double Potions; Free Time; Dinner in the Great Hall ;;