Back in Week 2 we talked about the challenges of interaction in mobile and ubiquitous computing contexts. And this week we're coming back to it in a different way – gestures. Gestures are often thought of as being a natural part of communication. Could they be a good fit for contexts were a keyboard and mouse is not really appropriate? This week we'll be covering some of the conceptual aspects surrounding gesture-based computing as well as some of the technical challenges involved.