Learning science helps to train students in observation, reasoning and argumentation, which are some of the foundations for all learning. It also helps improve transferable skills, such as logic, critical thinking and organisation. In order to develop an awareness of the complex interactions in contemporary society between science, technology, society, education and the environment, it is important to have an understanding of scientific practices and processes. This understanding also helps students to become active, scientifically literate citizens. With waning interest in science, technology, engineering and mathematics (STEM) among young people, OTTER aims to enhance understanding of education outside the classroom (EOC) methods and how they can be utilised to increase interest in STEM subjects among students and improve their acquisition of scientific knowledge and transferable skills. The project will connect EOC experts from Finland, Hungary, Spain and Ireland, strengthening networks within Europe and building a foundation for the development of EOC pilot schemes within the four focus countries. The effects of these pilots on the performance of participating students, including their levels of sophisticated consumption and scientific citizenship, will be analysed to better understand the effects of EOC on EU citizens. The pilots will build on recent momentum in tackling environmental issues and help to promote sophisticated consumption by incorporating a theme of reducing and managing plastic waste. The analysis will seek to identify differences in the effect of the programmes on students from different geographical locations and of different genders, comparing those who participated in the EOC pilot schemes with students who only participated in formal education. OTTER will further aim to improve accreditation of EOC teaching methods within Europe, contributing to the selection of accreditation tools available for use beyond the end of this project.