## 4 Learning Scenarios Using Sensors
### Human Activity and Sensors  
So far, we have discussed sensors that are a part of a device itself, _i.e._, pieces of technology. However, in some cases, where technology is mediating the experience and the experience is also collective, we could have the users performing the task of a sensor. For example, when users are sending tweets using Twitter, they could write something they have observed in their surroundings. The users can also express their feelings in the tweets. The students could use Twitter for creating a school-wide or nation-wide emotion channel. Students could be tweeting their emotions to a certain Twitter channel by marking their tweets with a hashtag, for example, #emotionNYC. The tweets could automatically be monitored, and a \"heat-map\" could be generated based on the time and the location of the tweets. Although not a sensor data augmented experience, the heat-map is a visualization of a collective experience that is mediated by technology.  
Nokia's Internet Pulse [48] is a web service for monitoring public opinion by tracking social network status updates and grouping the results based on positive or negative sentiment. Nokia's Internet Pulse presents the aggregated status updates in a timeline format as an interactive graph that allows users to drill down into the various search terms that correlate with the hot topics in Twitter feeds at selected time periods.  
[PERSON] _et al._[49] presented a pilot study on using collective heart rate visualized in an indoor ice rink to make intensiveness visible to an audience. The aim of the study was to explore the usefulness and effect of the developed collective heart rate and to evaluate it as one of the new features that could enhance the user experiences to audiences in wide public events. In particular, the study focuses on studying the significance of the technological equipment in creating a sense of collectiveness and togetherness for the audience. The results indicate that it is possible to enrich user experience in public events from user-generated data.  
In [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] [50], the audience is seen as an active part of large-scale public events, and one of the intentions of their study was to increase and enhance the interaction between the audience and the happenings in the event area. Audience members can be described as sensors, not just consumers, but producers and content creators, as well. With the concept of a collective emotion tracker, it is possible to invite the audience to participate in the event and give advice to other participants. In this study, participants sent location-based mood information to the server by using a custom-made mobile application or mobile web page. Moods formed a heat map of emotions. Furthermore, participants were able to select interesting ones from different venues from the mood heat map.  
Navigating unfamiliar, eventful environments, such as a festival or conference, can be challenging. It can be hard to decide what to see and when you have decided where to go; it can be difficult to know how to get there. While several research projects have investigated the mobile navigation of physical environments, past work has focused on extracting general landmarks from relatively static sources, such as structured maps. [PERSON], [PERSON] and [PERSON] [51] presented a system that derives points-of-interest and associated landmarks from user-generated content captured onsite. This approach helps users navigate standard environments, as well as temporary events, such as festivals and fairs. Using social networks and preference information, the system also gives access to more personalized sets of points-of-interest. This kind of collective experience system could enhance learning events, for example, in large camps or campus-wide events.