With increasing urbanization and urban sprawl around the world, we must make the cities people already inhabit more sustainable for current and future generations. A growing part of the sustainability discussion includes the relationship between the physical built environment and social sustainability. Woodcraft et al.  explain “social sustainability combines design of the physical realm with design of the social world – infrastructure to support social and cultural life, social amenities, systems for citizen engagement and space for people and places to evolve” (p. 16). The built environment has an immense impact on out quality of life and shapes how we interact with our fellow citizens - as Jan Gehl  describes “first we shape the cities—then they shape us” (p. 9).
Social sustainability can be advanced through changes in the built environment and participatory processes that support social life and inclusion such as the push towards ‘child-friendly’ cities. While young children are here-and-now citizens, many urban centres (and suburbs!) remain relatively unwelcoming or inaccessible to them and others. Child-friendly cities “take into account the rights and needs of the children who live in them to play and explore to ensure their present well being and long term health development” . Moreover, opportunities for children to participate in decisions that affect their lives has been largely overlooked by prevailing adult planning priorities and agendas in cities . As young children are active social actors , experts in their own lives  and capable communicators  their views provide a unique perspective on urban life.
Enhancing Communication & Participation Options
How can urban planners and designers enhance children’s participation in the design of cities? For one, it means meeting children where they are in their lives. This not only means physically but also acknowledging that children communicate their thoughts and ideas in diverse ways.
Children (like humans of any age) communicate messages in multiple ways, some with certain advantages (and limitations) over others. For example, the advantages of audio communication include enabling a tone of voice, accent or mood while video affordances could include showing a process, movement and the passage of time. Print (like this blog post), for example, is usually linear and can help express a sequence of events. Young children communicate their ideas in different ways that could include movement, speech, print, image, gesturing, and making sound effects among others (even using a combination together). In the education literature, this is commonly referred to as ‘multimodal communication options’ . Built environment practitioners should seek to expand rather than limit these communication options to enhance children’s participation in design processes. Studies suggest providing children a wide array of communication options affords them greater opportunities to participate in the discussion and design of spaces [9-11].
While research has explored young children’s participation in the design of public space [11-17] there has been some, but limited work that specifically identifies the benefits of multimodal opportunities for young children to communicate their ideas and participate in urban planning and design processes. Comber et al.  have worked across disciplines with architects, journalists, university students, educators, and children to build a curriculum around the (re)design of community buildings and structures. The research team provided children opportunities for the development of skills that could have “currency beyond the project” (p. 243-244). They identified children engaged in the project through different ways such as bodily, linguistically, materially and through multiple means of communication.
Another innovative program, Growing Up Boulder (GUB), is a partnership between the University of Boulder, the City of Boulder, the Boulder Valley School District and other community groups. The GUB program works with children from ages 0-18, and utilizes “creative multimodal methods for learning” . Methods of engagement in the GUB model include photography, mapping, drawing, digital presentations, and 3-D model making. Derr and Tarantini  highlight the “media-based methods...combined with curricular activities that increase student knowledge about a specific planning topic, actively engage participants, [and promotes] the dialogue necessary to understand children’s desires” (p. 1536-1537). The results of the numerous GUB programs suggest multimodal opportunities provide greater opportunities for discussion and expression of design ideas .
Malone’s  Dapto Dreaming project also suggests benefits of enhancing multiple modes for participation. Working with children aged 5-6 and 10-11, children were able to choose from a variety of methods (e.g., oral, mobile, written, visual) as a means of data collection about their school and neighbourhood. Malone identified “having a range of methods provided for flexibility in the field where children as co-researchers could identify which data collection methods provided the best fit between their own interests and skills and the context of the study and the study site” (p. 16). These examples all suggest providing a wide array of communication options affords young children greater opportunities to participate in the discussion and design of spaces.
Challenges & Opportunities
Incorporating children into planning and design processes can be difficult, time consuming and potentially costly. Moreover, as Yilmaz  identifies “the effectiveness of participatory planning is often evaluated based on physical outcomes, and these outcomes are an important part of the process. Yet the reality of many planning projects is that the timing of implementation often far exceeds children’s participation” (p.15). This concern is echoed by Clark  who argues “one of the challenges of conducting research with young children during real building projects is dealing with the length of time involved from early designs to completion” (p.100).
While large scale participatory projects may provide a big impact, smaller scale immediate change may be no less significant for young learners. Small scale interventions go by different names within the urban planning and design world (e.g., placemaking, tactical urbanism, pop-up projects, city repair, D.I.Y urbanism, guerilla urbanism, action-planning).
We at Design Outsider consider how could small scale interventions impact young children’s perspectives and provide an opportunity for them to communicate their ideas about their surroundings? This opportunity is highlighted by McGlone  who argues “the short-term, flexible and interactive nature of temporary public space potentially makes it an effective vehicle for facilitating children’s involvement in planning” (p. 124). Despite the meaning-making and participatory potential of built environment placemaking for children (Sutton & Kemp, 2002), it remains an underdeveloped focus of study.
This immediacy of short-term interventions could help counter what Sinclair  describes as ‘consultation fatigue’ (p. 113), where young children feel disillusioned if their participation does not lead to noticeable change. While long-term sustained programming and consultation with young children should be a key goal for built environment professionals - short term interventions should not be overlooked - as they are a clear opportunity for ‘quick wins’. By utilizing small scale interventions young children are given opportunities to expand their communication and participation options, while also seeing the immediate effects of their efforts to help design their environments towards a more sustainable vision. Young children - current citizens and neighbours in our communities deserve nothing less.
 Woodcraft, S., Hackett, T., & Caistor-Arendar, L. (2011). Design for Social Sustainability: A framework for creating thriving new communities, The Young Foundation, London.
 Carroll, P., Witten, K., & Stewart, C. (2017). Children are Citizens Too: Consulting with Children on the Redevelopment of a Central City Square in Auckland, Aotearoa/New Zealand. Built Environment, 43(2), 272-289.
 Gehl, J. (2010). Cities for people. Washington, DC: Island Press.
 Bishop, K., & Corkery, L. (Eds.). (2017). Designing cities with children and young people: beyond playgrounds and skate parks. Taylor & Francis.
 James, A., & Prout, A. (1997). Re-presenting childhood: Time and transition in the study of childhood. Constructing and reconstructing childhood: Contemporary issues in the sociological study of childhood, 2.
 Clark, A., & Moss, P. (2011). Listening to young children: The mosaic approach. Jessica Kingsley Publishers.
 Clark, A. (2005). ‘Ways of seeing: using the Mosaic approach to listen to young children’s perspectives’, in Clark, A., Kjørholt and Moss, P. (eds.) Beyond Listening. Children’s perspectives on early childhood services. Bristol: Policy Press, pp. 29–49.
 Kress, G.. (2000) “Design and Transformation: New Theories of Meaning.” Multiliteracies: Literacy Learning and the Design of Social Futures. Ed. Bill Cope and Mary Kalantzis. New York: Routledge. 153-61.
[9. Derr, V., & Tarantini, E. (2016). “Because we are all people”: outcomes and reflections from young people's participation in the planning and design of child-friendly public spaces. Local Environment, 21(12), 1534-1556.
 Derr, V., & Yilmaz, S. (2015). Effective means of communication for children and youth to have a voice in environmental decisions in their city. In Conference on Communication and Environment, Boulder, CO.
 Malone, K. (2017). Child Friendly Cities. In Bishop, K., & Corkery, L. (Eds.) Designing cities with children and young people: beyond playgrounds and skate parks, pp. Taylor & Francis.
 Comber, B., Nixon, H., Ashmore, L., Loo, S., & Cook, J. (2006). Urban renewal from the inside out: Spatial and critical literacies in a low socioeconomic school community. Mind, Culture, and Activity, 13(3), 228-246.
 De Visscher, S. (2015, August). The Ideal Child in the Ideal City? The City as Co-Educator. Paper presented at the RC21 International Conference on “The Ideal City: between myth and reality. Representations, policies, contradictions and challenges for tomorrow's urban life” Urbino, Italy. Retrieved from http://www.rc21.org/en/conferences/urbino2015/
 Derr, V., & Kovács, I. (2015). A case study of neighbourhood design from Boulder, Colorado, USA: how participatory processes impact children and contribute to planning. Journal of Urbanism: International Research on Placemaking and Urban Sustainability, 10(1). 29-48. doi:10.1080/17549175.2015.1111925
 Malone, K. (2013). ‘The future lies in our hands’: children as researchers and environmental change agents in designing a child-friendly neighbourhood. Local Environment: The International Journal of Justice and Sustainability, 18(3), 372–395. doi: 10.1080/13549839.2012.719020
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 McGlone, N. (2016). Pop-Up kids: exploring children's experience of temporary public space. Australian Planner, 53(2), 117-126.
 Clark, A. (2010). Young children as protagonists and the role of participatory, visual methods in engaging multiple perspectives. American Journal of Community Psychology, 46(1), 115–123. doi: 10.1007/s10464-010-9332-y
 Sutton, S. E., & Kemp, S. P. (2002). Children as partners in neighborhood placemaking: lessons from intergenerational design charrettes. Journal of Environmental Psychology, 22(1-2), 171-189.
 Sinclair, R. (2004). Participation in practice: Making it meaningful, effective and sustainable. Children & society, 18(2), 106-118.