An academic year, or school year, is a period that schools, colleges and universities use to measure the duration of studies for a given educational level. Academic years are often divided into academic terms. Students attend classes and do relevant exams and homework during this time, which comprises school days and school holidays. The duration of school days, holidays and school year varies across the world. The days in the school year depend on the state or country. For example, in most of the US states, there are 180 days in a school year, but in the US state of Minnesota there are 165 days in the year.