Children in separate schools get on with things regardless of it being work for boys or girls, which can be quite positive especially in today's lifestyles where chores are done across the board.

across 在这里是介词，表示"横跨、遍及"的意思。 the 是定冠词，特指某个范围或群体。 board 原意是"木板"，在这里引申为"全体人员"或"整个范围"。 across the board 是一个固定短语，意思是"全面地、无一例外地"，指涉及某个范围内的所有方面或成员。