\section{Mission Possible: Ubiquitous Social Goal Sharing}

This paper presents a pilot study using ambient displays to provide near real-time visual feedback on physical activity in a school environment. 

\section{Participants}
All children within Year 5 (9-10 years old) from Bigyn Primary School in Llanelli were invited to take part in the study (n=32). Available resources dictated that this was the maximum number of participants that could be recruited to pilot the intervention, thus statistical methods were not used to determine samples sizes and no control group was measured. Written informed parental consent and participant assent were received from all children (100\% participation rate).

\section{Outcome Measures}
Ethics approval to conduct the study was obtained from Swansea University's A-STEM (Applied Sports Technology Exercise and Medicine Research Centre) ethical advisory committee. After securing the co-operation of the school, all Year 5 children were invited to take part via an information sheet and parents were provided with a consent form to complete if they wanted their child to participate. Additionally, children provided informed assent. 
Baseline data collection measures were completed in April 2013 and post-intervention measures were completed after the 4 week intervention period in June 2013. Children completed the Physical Self-Perception Profile for Children (PSPP-C) \cite{Whitehead1995}. Stature and sitting stature to the nearest 0.1cm (Seca Ltd. Birmingham, UK) and body mass to the nearest 0.1 kg (Seca Ltd. Birmingham, UK) were measured using standard techniques \cite{Lohman1988}. Body mass index was calculated (body mass (kg) / stature2 (m2)) and BMI z-scores were assigned to each participant \cite{Cole1995}. Waist circumference was measured to the nearest 0.1 cm using a non-elastic anthropometric tape and measurements were taken at the narrowest point between the bottom of the ribs and the iliac crest. All measurements were undertaken by the same trained researchers. The 20m shuttle run test was conducted to provide an estimate of cardiorespiratory fitness (CRF). This test has been widely used in children of similar age \cite{EUROFIT1998,Stratton2007,vanmechelen1986}. The total number of completed 20m runs was used as a marker for CRF.
Data were analysed using a mixed ``between-within'' analysis of variance (ANOVA), with group as a between-participant factor and time as a within-participant factor. Statistical significance was accepted at P<0.05. All statistical analyses were conducted using IBM Statistics 21 (SPSS, Chicago, IL). All data are presented as means $\pm$ SD. Statistical significance was accepted when P $\leq$ 0.05.

\section{Intervention}

The design of Mission Possible draws on the principles discussed in the previous section, but differs in a number of key ways from most of the ubicomp technologies. Firstly, Mission Possible allows school children to reflect on the process of increasing their activity levels for each day of each mission in a playful way. Children have to work as a team and ensure that a representative of their team is wearing the Fitbit; there is no requirement for data entry (as is needed for diarisation). Secondly, children get the reward of seeing their activity data without having to make any initial effort, or to remember to switch the recording function or the display on and off. They just have to clip on the Fitbit - the ambient display is already part of their schoolroom environment. 

A third difference concerns goal-setting. Formal goal-setting, training and coaching are replaced in Mission Possible by users’ engagement with the information on the ambient display in terms how their team is performing and includes performance of the other teams. As a result, rather than feeling that they are engaging in a formalised exercise program (e.g. physical education), children are allowed to respond to this information in whatever way they wish. As argued by Thaler and Sunstein \cite{ThalerSunstein08}, behavioural feedback forms part of the choice architecture that nudges behaviour. In this case, the feedback from the ambient display nudges children to be little bit more active than a day before; having the LED display right at the front of the classroom allows them to occasionally glance at their performance data during the day.

The fourth difference concerns the structure of the social interaction. Almost all of the work reviewed in the social sharing section focused on participants remotely contributing to their team's goal. For example, Into, Fish'n'Steps, Houston, Shakra and Chick-Clique individual members of teams have a physical activity monitoring device, set goals as an individual or a team and work toward those goals remotely through a digital medium (no face to face interaction with team members happens). Mission Possible breaks away this individualistic digital bubble phenomenon \footnote{Also called Mindless Technology by Professor Yvonne Rogers in her keynote speech at INTERACT 2013 \url{http://www.interact2013.org/Keynotes}} and allows children through shared Fitbits and the ambient display, to be more creative, playful and thoughtful of each other.

Although it differs from other ubicomp technologies in the respects listed, Mission Possible shares with them the desire to be interesting and fun to use. To this end, Mission Possible draws on the experiences and lessons of other systems. It gives positive reinforcement (learning from the success of UbiFit Garden and Houston and from the problems experienced by Fish’n'Steps); similar to Houston, Chick Clique, UbiFit Garden, Into and Shakra, provides opportunities for teams to reflect on their activity. Finally, like the social gaming and social data sharing features of Fish’n’Steps, Houston, Chick-Clique, Shakra and Into, the social norms information within Mission Possible is designed not only to prompt increased physical activity, but also to encourage engagement with the feedback i.e. the displays of their team and others’ activity levels.
The intervention design and content were informed by formative work with the children involved, thereby employing a user-centred design. The children were divided into four groups, where each group generated ideas for possible missions. These included ideas like:
\begin{itemize}
\item playing tag with laser guns, bouncy balls or velcro stars
\item who can do the assault course the fastest
\item ``aliens vs. cowboys'' or ``zombies vs. humans''
\item capture the flag
\item hide and seek using climbing wall

\end{itemize}

 We selected feasible ideas from the lists, and generated descriptions of the missions based around a ``secret agent'' type theme:

\begin{itemize}
\item Mission 1: Assault course - ``Captain Cybernetic wants you to infiltrate Dr. Tempus's lair. However, Dr. Tempus has placed various obstacles in your path. Navigate the obstacles to get to his lair as fast as possible.''
\item Mission 2: Code hunters - ``A video clue is shown on the iPad, where you have to find a hidden token. The token must be returned to the teacher, who will reveal the next video clue the following day. The tokens from Monday to Thursday will be needed to find the final token on Friday.''
\item Mission 3: Capture the flag - ``Two teams; where each team tries to get the other team's flag while protecting their own.'' 
\item Mission 4: A race against time - ``Captain Cybernetic has gained access to a high-power laser beam that is powered by your feet. You and your teammates need to work together to rack up as much steps as possible. Your step count will be used together to power the laser beam and destroy the evil Dr. Tempus's lair.''
\end{itemize}


\subsection{Design and methodology}

Children were divided into 10 groups, where each group was assigned a uniquely distinguishable colour to represent their group on the ambient display. Flexible LED lighting was installed along the bookshelf in the front of the classroom. 

The display was connected via a microcontroller to the school's computer network. Activity monitor data were retrieved from the Fitbit website and displayed with moving colour segments, where different colours were used to represent the various teams. The teams could make their colour segment go faster by increasing their number of steps. The team's colour would start to flash if the spent more time being active than the previous day.

For the missions, ideas were elicited directly from the schoolchildren, with a brainstorming activity performed at the school. These ideas were then refined by the project team and turned into four activity-based missions.

\subsubsection{Hardware design}

Ambient displays located in a person's environment have been shown to change their behaviour by providing live feedback \cite{fan2012,harries2013}. These displays serve as decorative visual art pieces intended for reflection.

An ambient display, consisting of a 4m-long lighting strip with 240 individually controlled LED lights, was designed and constructed by Swansea University and installed in the classroom. Data collected from 10 Fitbit activity monitors were visualised on the lighting strip with different lighting patterns. The ambient display connects via a network cable to the Internet in order to download the Fitbit data. 

To visualise the performance of each of the 10 groups, uniquely distinguishable moving colour segments were used. Each colour segment had a speed betwen 0 and 10, based on the group's performance. To calculate the speed of each group we used the following formula:

\begin{equation}
v = 5 \frac{x}{y} + 1  
\end{equation}

where $v$ is the speed at which the segment is moving, $x$ is the accumulated number of steps taken that day, and $y$ is the number of steps taken on the previous day. On the first day of each mission, $y$ was set to 1000 as a default value.

To provide additional encouragement for the children, we used the intensity level (lightly active, fairly active and very active) while they were performing the missions. We compared the number of minutes they spent at the `very active' intensity level to complete the mission on that day with the previous day. If they were doing more vigorous exercise than the previous day, their group's colour segment would start pulsating. 

A DVD outlining the various missions, together with a Teacher’s Guide mission pack, was provided to the teacher, and the mission videos installed on a set of tablets belonging to the school.

\subsubsection{Measurement of physical activity}

The Fitbit Zip (Figure \ref{fig:Fitbit}) contains a tri-axial accelerometer to record time-stamped physical activity data, including number of steps and physical activity according to four levels: sedentary, lightly active, fairly active and very active. It can be clipped to various locations on the body. For the study we asked participants to clip the device to the inside of their trouser pocket. The Zip is designed to be small and unobtrusive, making it more acceptable for use by children than other activity monitors which are often large and bulky. A recent study \cite{m_Noah_Spierer_Gu_Bronner_2013} has indicated that the Fitbit is reliable and valid for activity monitoring (in terms of step counts).
 
Data from the activity monitors were uploaded automatically to Fitbit's servers as the children returned from completing the mission for the day, via a Bluetooth Low Energy (BLE) dongle connected to a computer in the classroom. Data was accessed using the Fitbit API, analysing the results and storing them on the university's server. The results were then downloaded by the Arduino (see Figure \ref{fig:arduino}), connected with an Ethernet shield to the internet via the school's network. Note that the activity monitor was worn from the start of the activity until the end of the activity, and not the entire day.

The Fitbit trackers syncs to the Fitbit servers every 15-20 minutes, as long as they are within 15 feet (approximately 5 metres) of the BLE dongle. Each Fitbit tracker has its own ID, which means that one BLE dongle can sync multiple devices. Whenever new data is available on Fitbit's servers, it is synchronised with our university server. It takes approximately 1-2 minutes to transfer all the activity data from the Fitbit servers. The Arduino polls the university server every 5 minutes for the results to be displayed on the ambient display.