How many lessons/periods is there at Hogwarts and what would the sixth year

[edwardcullensegirlfriend]

timetable be? [Harry's year]? I know that on a Monday, Hermione has:
P1 Ancient Runes
P2 DADA
Break
P3 Arithmancy
P4 ?
Lunch
P5 Free
P6 Double Potions