Expertise to assist people on complex tasks is often in short supply. One solution to this problem is to design systems that allow remote experts to help multiple people in simultaneously. As a first step towards building such a system, we studied experts' attention and communication as they assisted two novices at the same time in a colocated setting. We compared simultaneous instruction when the novices are being instructed to do the same task or different tasks. Using machine learning, we attempted to identify speech markers of upcoming attention shifts that could serve as input to a remote assistance system. Categories and Subject Descriptors H5.3. [Information interfaces and presentation]: Group and Organizational Interfaces ? collaborative computing, computer-supported cooperative work. General Terms Experimentation, Human Factors. Keywords Remote collaborative physical tasks, video-mediated communication, remote expertise, multi-party conversation, focus-of-attention, mult...