When teaching computer science it can be easy to focus on details and lose sight of the bigger picture. This is particularly concerning with new pretertiary curricula being adopted in many countries as teachers grapple with a bewildering array of topics to teach. This paper steps back and introduces a list of ten big ideas of computer science that have been distilled based on input from curriculum designers and computer science education experts around the world. The big ideas are presented in a way that a classroom teacher will be able to engage with, so that they can use them to relate topics that they teach to the context of a bigger picture.