The pandemic in spring 2020 required a sudden change to online conferencing for the Young ERME Summer School (YESS) of the European Society for Research in Mathematics Education (ERME). So YESS was re-organised offering two Thematic Working Groups (TWG) for five days using an online meeting tool. However, little research knowledge was found to draw on: research on educating young researchers in this field is scarce (Kontorovich & Zazkis, 2015) and little is known about how participants manage their participation in online conferences, and how these conferences are designed and experienced (McBrien et al, 2009). Therefore, YESS-online was conducted as a design research project to investigate the students’ experiences with this format. Because the participants belonged to various geographical spaces and time zones we expected that boundary crossing would be essential parts to deal with when meeting in the virtual space (Akkerman & Bakker, 2011), for example boundary interactions between social practices of YESS, and family. Our investigation focused on students’ experiences with regard to their boundary interactions, the boundary objects used in the course and how they proceeded in their research projects.

The sessions were designed to enculturate early career researchers from Europe and beyond into research as an “epistemic inquiry unfolding the research object as an epistemic object” (Bikner-Ahsbahs, 2017, p. 155) practised in two TWG-communities, which were guided by experts and supported by two brokers (young researchers). A tool to guide this epistemic enquiry, the research pentagon, was introduced to the students to think and reflect about research in terms of interrelated research aims, questions, objects, methods and situations.

This pentagon served as a boundary object for students’ interaction that was rhythmically organised in ten sessions leading to giving and getting feedback in various ways. Drawing together, we expected the students’ experiences be influenced by three essential conditions: by the boundary crossing which was possible via the virtual space, the way the students experienced the use of the research pentagon and its rhythmical organisation in the sessions. In the symposium, these conditions are addressed and interlinked to answer the following two overall research questions:

• How was the rhythm of the use of the pentagon, feedback and interactions organised and experienced?
• How were the boundaries and efforts of dealing with boundaries related to the rhythm of the use of the pentagon, feedback and interactions?

Methodically, the three perspectives guided collecting and analysing the following data: design and evaluation materials, notes taken during the sessions and video recorded interviews with eleven volunteers from the two TWGs. The video recordings were transcribed, the transcripts were analysed in three steps:

• guided by the concept of boundary crossing and the pentagon as a boundary object, each interview was interpreted using the theoretical framework by three researchers and finally summarised.
• these summaries were compared and contrasted with respect to the students’ experiences of the creation of the social spaces (Lefebvre, 1991) in the TWGs.
• A rhythm analysis (Lefebvre, 2004) was conducted, first following the answers of each single interview and then comparing rhythmic parts between the interviews.

 Our main results show that boundary setting proves to be crucial in students’ participation, in particular between home and conference practices. Thereby, rhythm in the use of the pentagon, feedback giving and getting and interaction plays an essential role in guiding the students’ experience of increasing intensity and for empowerment (Zimmerman, 1995) in their learning experiences, however the pentagon must be individually instrumented (Trouche, 2020) requiring a responsive orchestration.

The three papers of the symposium will present research about the students’ boundary crossing, experiences of instrumentations of the research pentagon and the rhythm of pentagon use.

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