The purpose of this study is to investigate teachers' practices and views of STEM activities for children aged 4-7 years old. The participants are 18 Greek teachers and data is collected via interviews. Commonly reported reasons for the importance of STEM education are the development of skills, knowledge, and children's interest for learning, while the skills children develop, include collaboration, communication, socialisation, problem-solving, experimentation, critical thinking, programming, creativity, and language/literacy. STEM activities implemented in class are programming, robotics and interdisciplinary activities, as well as experiments and exploration of materials. The primary factors considered when preparing STEM activities are children's interest-motivation, their cognitive level or age, and the learning outcomes. Teachers' perceived challenges mainly regard experiential learning, children's interest and active participation, while main problems include limited time, infrastructure, and teacher training. Implications for educational policy-practice and teacher training are discussed.