Feedback Unbound: from master to usher.

A major theme of this book is that feedback should encourage dialogue; between students and lecturers, amongst peers and individually, as a form of self-critique and reflection. Here we endorse that theme but also propose an understanding of dialogue that goes beyond simple exchang or the presence of two or more voices. Inspired by Freire’s (1996) critical pedagogy we seek to make a link between the social nature of learning, the social nature of dialogue and the role of feedback as dialogue in a broader transformative learning process, and not merely as an adjunct to assessment.

A decentralized batch-based group key management potocol for mobile Internet of Thngs (DBGK).

It is anticipated that constrained devices in the Internet of Things (IoT) will often operate in groups to achieve collective monitoring or management tasks. For sensitive and mission-critical sensing tasks, securing multicast applications is therefore highly desirable. To secure group communications, several group key management protocols have been introduced. However, the majority of the proposed solutions are not adapted to the IoT and its strong processing, storage, and energy constraints. In this context, we introduce a novel decentralized and batch-based group key management protocol to secure multicast communications. Our protocol is simple and it reduces the rekeying overhead triggered by membership changes in dynamic and mobile groups and guarantees both backward and forward secrecy. To assess our protocol, we conduct a detailed analysis with respect to its communcation and storage costs. This analysis is validated through simulation to highlight energy gains. The obtained results show that our protocol outperforms its peers with respect to keying overhead and the mobility of members.