This work emphasises the long-standing focus on democratisation in the participatory design field by analysing how participation can be achieved (the pragmatics of participation) and how participation can be increased (the politics of participation) through malleable interactive prototyping. Malleable interactive prototyping refers to the design of digital prototypes of IT systems that are open enough for a designer and a user to collaboratively design and re-design. The interactiveness allows the user to experience the interaction with the system and its design and also allows for redesign during the interaction. This type of prototyping is explored in the collaborative design of an IT system between a designer and citizens at a hospital, and in a short series of co-design workshops with young learners as designers within a component of their digital competence education in upper secondary school. Through a qualitative analysis, this work demonstrates that malleable interactive prototyping increases participation and participatory design. Four conclusions are proposed for the participatory design field: malleable interactive prototyping gives users an informed voice in the design process, allows users to collaboratively design an IT system with a designer, facilitates mutual learning between designer and user, and increases the ecological validity of the collaborative design. Furthermore, the explorations contribute to the education field by showing that malleable interactive prototyping can explicate future use and the user as well as the role of the user and the IT system for young learners, thus enabling young learners to experience democratic IT systems design processes. These conclusions suggest that school policy writers should consider including a socio-technical perspective in the computational-focused curriculum and that educators should contemplate the delivery of this education across all programmes.