The site-specific installation IDEN produced for the school ‘Le collège des Mûriers’ in Colombier, Switzerland responds to theme ‘numbers and letters’ requested for the competition. For this intervention we wanted to get closer to the children’s universe while integrating the building architecture. So, we installed a small door identical to the others ones of the school. This door is always locked and one can read on it: ‘Take care of the sense, and the sound will take care of themselves’, a quote from Lewis Carroll book ‘Alice in Wonderland’. This installation symbolised the idea of ‘passage’ or ‘crossing’; from learning to reading, from child to adult, from reality to fiction.