Computer science is becoming ever increasingly important to our society. Computer science content has, however, not traditionally been considered a natural part of curricula for primary and secondary education. Computer science has traditionally been primarily a university level discipline and there are no widely accepted general standards for what computer science at K-12 level entails. Also, as the interest in this area is rather new, the amount of research conducted in the field is still limited. In this paper we review how 10 different countries have approached introducing computer science into their K-12 education. The countries are Australia, England, Estonia, Finland, New Zealand, Norway, Sweden, South Korea, Poland and USA. The studied countries either emphasize digital competencies together with programming or the broader subject of computer science or computing. Computational thinking is rarely mentioned explicitly, but the ideas are often included in some form. The most common model is to make computer science content compulsory in primary school and elective in secondary school. A few countries have made it compulsory in both, while some countries have only introduced it in secondary school.