This paper reports on the results of a study of teacher preparedness and practices in relation to teaching computing and computational thinking at schools in Sweden, Finland and Lithuania. The study was conducted as part of a NordForsk funded project to explore how Computing Education Research in the Universities can help the development of teacher training and K-12 curriculum and teaching practices. The study found that many teachers are already engaged in teaching relevant material in the schools, and that many have good support in their local school environment. However, there are also significant challenges which emerge from the new curricula that have been introduced in Sweden and Finland. To meet these challenges new teacher training programmes will be needed, and we recommend that computational thinking and computing concepts be introduced into the core subject content of teacher education programmes in order to better prepare teachers to meet the educational demands of our increasingly digitalised society.