This issue of "Education Indicators in Focus" reports that Organisation for Economic Cooperation and Development (OECD) countries organise learning time for primary and secondary education in different ways: (1) The number and length of school holidays differs significantly across OECD countries, meaning the number of instructional days in primary and secondary education ranges from 162 days a year in France to more than 200 days in Israel and Japan; (2) The higher the level of education, the greater the number of instructional hours per school day. Students in OECD countries are expected to receive on average 4.3 hours of instruction per day in primary school, rising to 5.2 hours in upper secondary school; (3) On average across OECD countries, around half of primary schools' compulsory curricular time is focused on reading, writing and literature; mathematics; and science, amounting to 2.2 hours per school day. In lower secondary education this falls to only 1.8 hours per day; and (4) There are wide variations across OECD countries in the organisation of the learning time within and outside the classroom but there has been a recent trend of increasing classroom instruction time dedicated to core subjects such as mathematics, and a reduction in the time spent doing homework outside the classroom. The brief concludes that the number of instructional hours students are expected to receive during compulsory education and the length of the school year vary significantly between countries but in general the higher the level of education, the greater the number of instruction hours per school day. In many countries, primary and secondary students have homework to do and can participate in after-school lessons to complement their learning time. Matching resources with students' needs and making optimal use of time are central to education policy but the wide variation across OECD countries in the organisation of the learning time within and outside the classroom suggests that countries have not worked out what the evidence says about the most effective use of students' time.