This thesis looks at the accessibility of collaborative learning and the barriers to engagement experienced by blind/visually impaired (BVI) students and deaf/hard of hearing (DHH) students. It focuses specifically on online synchronous collaborative learning after establishing that this format presented the greatest barriers, and that these student groups were not engaging.

Taking a design-based research (DBR) approach, five studies were undertaken to identify these barriers and determine potential interventions. The product of the research, a result of collaborative design by the participants in the study, is a framework for accessible collaborative engagement represented in the form of an interactive website model, the Model for Accessible Collaborative Engagement (MACE).

The studies involved representatives of all stakeholders in the collaborative learning process at the institution (the Open University): students, tutors, modules teams, academics, support staff, and the student union Disabled Students Group. These studies took the form of an online survey of 327 students, 10 interviews with staff and students, 6 staff workshops and a collaborative design focus group. With significant representation of the target groups (BVI and DHH) in all studies, and taking an iterative approach to the design, evaluation and construction of the framework model, the studies established that barriers existed in four main categories covering different themes:

1. Communications: aural, visual, screen reading and navigation, text and captioning, lip reading and non-verbal communications, interpretation and third-party communications, mode control, and synchronisation.

2. Emotional and Social Factors: familiarisation, support networks, self-advocacy, opting out, cognitive load, and stress and anxiety.

3. Provisioning and Technical Factors: dissemination, speed and pacing of sessions, staff training, participation control, group size, technical provisioning, and recordings.

4. Activity and Session Design: Volume of materials, advance materials, accessible materials, accessible activities, and session formats.

Interventions were designed that could reduce the barriers in each of these categories and themes by adjustments and changes from both the student and institutional standpoints. MACE is designed to be utilised by both students and staff to provide guidance and suggestions on how to identify and acknowledge these barriers and implement interventions to reduce them.

This research represents an original and essential contribution to the field of investigation. As well as informing future research inquiry, the model can be used by all participants and stakeholders in online collaborative learning to help reduce barriers for BVI and DHH students and improve inclusivity in synchronous online events.