Let’s Chalk is a proposed interactive art installation and mobile app that allows people in different cities to draw on a shared digital sidewalk. The project was inspired by public art installations, collaborative art projects, and seeing people interact across distances. Early tests found that a camera and projector could share drawings, but the surface would need shade and to be painted white. Interviews informed the design details. The mobile app would let users see shared drawings and chat, while the website archives past drawings and promotes future connections between cities. Usability testing improved the app interfaces.

1. Let’s Chalk!
CHI 2013 Student Design Competition:
Supplementary Materials
Matthew Jennex, Stephanie Louraine, Stephen Miller, Angélica Rosenzweig Castillo
Indiana University, Bloomington, Indiana, USA

2. Table of Contents
1
Primary Research
1
Observations
3
Feasibility Test
5
Interviews
6
Design Inspiration
8
Early Ideation
9
Project Phase 1
10
Let’s Chalk!
12
The Opportunity
13
Wireframes
13 Mobile App
Website
16
18 Usability Testing
19
References
The High Line, New York City, NY, USA

3. Primary Research
Observations
Monon Trail, Broad Ripple, IN, USA
Cultural Trail, Downtown Indianapolis, IN, USA
Our first-hand observations of four different greenway systems revealed important characteristics of greenways
and their users. Our observations supported the claims we had found in our secondary research; greenways
are unique public spaces that act as an aesthetic experience themselves. Users of greenways are more likely to
engage and interact with each other than they would be in a different environment.
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4. Primary Research
Observations
High Line, New York City, NY, USA
Paseo de la Reforma, Mexico City, Mexico
Our observations helped us understand certain characteristics of greenways critical to our design to be consistent
between four different cities and two countries. We found large public art displays; volunteers taking an inventory
of local flora; community improvement efforts such as bike rental; and public education projects. In short, we found
greenways were public places the local community engaged with in a more than superficial way.
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5. Primary Research
Feasibility Test
Our design relies on a camera/projector system to share the Let’s Chalk square with the partner city; it was critical
for us to figure out if this idea was feasible in the least. We were able to determine that it was possible, but our test
showed us a few problems for which we would have to account. We determined the chalking surface ought to be
painted white in order to maximize contrast and visibility in the projections. We also realized an awning of some
sort would be necessary in order to block direct sunlight on the chalking area.
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6. Primary Research
We ourselves took the opportunity to play a little...for science! Not only was it fun, but helpful to our design. We
discovered that while sidewalk chalk is easy to use, one uses up a single piece rather quickly. A reliable, easily
accessed source of chalk will be absolutely necessary to the success of our design.
For a pilot test, we left behind some fresh sidewalk chalk pieces in a location on Indiana University’s campus.
A couple of days later we found a message someone else had left behind with our chalk. This showed us that
sidewalk chalk itself invites use.
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7. Interviews
Local Public Art Project Manager
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First hand experience developing a large, public, and collaborative project
Confirmed volunteers participate and help maintain exhibit
Explained common methods of procuring funding for public projects
Provided insights as to how cities deal with vandalism of public exhibits
Detailed the work that is required to get permission from a local government for a public project
Licensed Architect
»» Demonstrated a trellis design that would allow rain water through while maintaining unbroken
shade coverage
»» Offered suggestions on construction and layout of a Let’s Chalk installation
Trellis design
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8. Design Inspiration
Brain Extravaganza (http://www.jbtbrains.org/)
http://www.wherethehellismatt.com/
Our sources of design inspiration were critical in helping us decide how to execute and frame our design. One of
our main inspirations is the recent Brain Extravaganza! public art project undertaken by Dr. Jill Bolte-Taylor and her
colleagues in Bloomington, IN. The Brain Extravaganza! was 22 large, anatomically correct brain sculptures placed
around the city of Bloomington, IN in order to raise awareness of brain health. The Brain Extravaganza! was meant
to be beautiful, entertaining, educational, and interactive.
Another source of inspiration is the “Where the Hell is Matt?” project from Matthew Harding. It is a straightforward
idea - he travels the world and films himself doing a rather silly dance with local people. It sounds simple, but for us
proved to be a powerful exemplar. Matt demonstrated that even just seeing people from other places can have a
strong and lasting impact. This insight lies at the center of the collaborative aspects of our design.
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9. Design Inspiration
High Line Projector,
New York City
Sidewalk Chalk Art [2]
Centro de Cultura Digital,
Mexico City
Chalk It Up, Sacramento, CA, USA [1]
We also drew inspiration from photos of sidewalk chalk festivals. Many cities hold annual community events during
which participants come to play with sidewalk chalk and spend time with other community members. Events like
Chalk It Up encourage individuals to come and create their own sidewalk chalk art or contribute to a community
sidewalk square. Chalk It Up also brings in local artists to create masterpiece squares for everyone to admire.
Our observations showed us a couple of other examples of efforts using similar technologies - outdoor projectors,
interactive community art projects, dedicated spaces for play. These served as encouragement for our design as
we hashed out the details.
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10. Early Ideation
Choose your own scenic view
Collaborative painting and chalking
Active LED path
Share Wall
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11. Let’s Chalk First Iteration
An early imagining of a Let’s Chalk installation
An early scenario: John and Stacy have been in a long-distance
relationship for the past 6 months. One day, John in New York tells
Stacy to go to the Let’s Chalk! installation on a greenway in San
Francisco at 5pm. She visits it and sees he’s written a message
for her, and she can see him projected onto the sidewalk as well.
Touched, she writes him a message in return.
Signage for the installation
Another early Let’s Chalk sketch
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12. Let’s Chalk!
An imagined installation on the B-Line in Bloomington, IN

13. Let’s Chalk!
A second view of the installation

14. Community
Place
Opportunity
Play
The framework that defines the opportunity space our design occupies. Community is constrained by place, and
place is shaped by that community. The community and place also determine the form of play members take part
in. That play, in turn, shapes both the community and the place.
As an example: A group of friends (community) plays in a gymnasium (place). The play (basketball) shapes both the
community (now an ad hoc basketball team) and the place (now a basketball court).
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15. Mobile App
From our extended abstract:
“If the Let’s Chalk installation provides
the surface interaction of the system,
the mobile app provides a more in-depth
interaction. Its purpose is to provide
sharing and communication options that
give more meaning to the interpersonal
aspects of the surface interaction.
The app also serves a support role by
allowing users to report problems with
the installation.”
Having access to the Let’s Chalk
mobile application is not a prerequisite
for playing with the installation. It will
be advertised with a QR code on a
display at the installation. It will also be
linked on the Let’s Chalk website for
download.
Click here for an interactive wireframe of
the Let’s Chalk mobile app.
Home Screen
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16. Mobile App
Save to
Images and
Share buttons
The Sidewalk
Partner City Schedule
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17. Mobile App
Report abusive
messages in the
chalk chat.
Options to report
more frequently
anticipated types
of problems.
Other would
connect to a text
field to allow the
user to write a
specific message.
Anonymous user
names in the Chalk
Chat. Users will be
identified only by
the city they are
in and a number
according to the
order in which they
entered the chat.
Report a Problem
Chalk Chat
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18. Website
While the mobile app is meant to enrich
the in-the-moment interaction, the
website will most likely be used by those
who are either about to visit or have
already visited a Let’s Chalk installation.
Because of this, we designed our
website with three specific goals in
mind: we want to afford our users an
opportunity to reflect on the experience;
inform them about the project - why,
what, and where; and encourage them
to return to the installation.
The main page provides our primary
reflection tool - a gallery of the pictures
of the shared chalking square, called
“The Sidewalk.” The sidewalk would
include all of the images captured from
the current city partnership. A user
could switch to different partnerships
sidewalks, or view the sidewalks from
past weeks. Also on the home page
are ways to share the sidewalk images
and information about upcoming
partnerships.
Click here for an interactive wireframe of
the Let’s Chalk website.
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19. Website
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20. Usability Testing
Our usability tests focused on our mobile application. As
a result, we changed wording and layout on the home
page and the “Report a Problem” screen.
The usability tests were a medium fidelity paper
prototype conducted in a “Wizard of Oz” style.
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21. References
[1] Couse-Baker, Robert. “Chalk-It-Up! Sacramento 3.” 2 September 2012. Online image. Flickr. January 6, 2012.
[2] sankax. “Chalk it up.” 26 February 2009. Online image. Flickr. January 6, 2012.
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