A successful international learning initiative focusing on student agency began with a link facilitating OE-enhanced teaching between a UK university and a US high school class. It became an international trip organised and funded by five UK students and their teacher who travelled to California, teaching and performing music across formal and informal learning settings. The project is now a credit-bearing class, retaining the original initiative's openness within the university curriculum where final-year students collaborate with the teacher, self-organising to design and plan curricular details from travel logistics to musical interactions. Students engage in heutagogy, demonstrating the highest levels of autonomous, personal learning in this co-learning environment. Their assessment, a reflective journal, encourages engage with deeper learning processes. The original trip was documented as an eBook including 10,000 student-authored words telling their collaborative learning journey. The book was published without DRM an accessible model for other students and educators. [This paper was presented at the 2018 Open Education Consortium Global Conference, held in Delft (The Netherlands) April 24th-26th, 2018.]