I'm leaving work and I'm not sure whether to say I currently work with 2-4 year olds or 2-5 year olds. I've always said 2-4 (until they go to school ie. Until they are 4+) but I saw a preschool ad the other day which said '2-5 years old' which made me think does 2-4 years old mean from 2 until they are 4 or including 4, until they leave for school?