(1) Subject to paragraph (5), every day on which a school meets shall be divided into two sessions which shall be separated by a break in the middle of the day unless exceptional circumstances make this undesirable.
(2) At least 380 sessions shall be held at a school during any school year so however that nothing in this paragraph shall require a nursery class to meet for that number of sessions.
(3) Where at any time a school is prevented from meeting for one or more sessions for which it was intended that it should meet, and it is not reasonably practicable for arrangements to be made for it to meet at an alternative time for those sessions, the school shall be treated for the purposes of paragraph (2) as if it had met as intended.
(4) Subject to paragraph (5), on every day on which a nursery school or nursery class meets there shall be provided at least three hours of suitable activities:
Provided that on a day on which a pupil—
attends a nursery class which meets for only a single session; or
attends a nursery school or class for one only of two sessions,
it shall be sufficient to provide him with one and a half hours of suitable activities.
(5) In a school which meets on six days a week there may on two of those days be only a single session and, in relation to a day on which there is only a single session, paragraph (4) shall have effect as if the period of three hours there mentioned were a period of one and a half hours.