When many students think about environmental sustainability, they picture recycling bins, solar panels, or campaigns to reduce litter. These efforts matter. But they only tell part of the story. One of the most powerful things we can teach young people is that sustainability is fundamentally about how we design systems — and that cities are some of the most instructive systems we have.
Cities concentrate people, resources, problems, and possibilities in ways that make the stakes visible. They also make the design choices visible. When a city floods repeatedly, or bakes in summer heat, or loses its green space to pavement, those are not accidents. They are the result of decisions — decisions that can be studied, questioned, and reimagined.
This piece explores how educators can use real cities as case studies for teaching:
Environmental literacy
Systems thinking, and
Design.
As the world evolves at a rapid pace — upending economies, industries, and communities — grounding students in these three areas may be one of the most important investments we can make in their professional, civic, and personal futures.
Why Cities?
Cities are where most of the world’s population now lives. They are also where the effects of climate change are felt most intensely — through urban heat islands, flooding, air quality crises, and unequal access to green space. At the same time, cities are where some of the most ambitious environmental design work is happening.
For students at any level, cities offer something textbooks often cannot: a real system to examine. Every neighborhood has a history of decisions. Every park, drainage canal, vacant lot, and rooftop represents a choice someone made — or a choice no one made. Learning to read a city as a designed system is a skill that transfers across disciplines and careers.
Five Cities Worth Studying
These cities are not perfect models. Each has made mistakes, faced tradeoffs, and is still learning. That is part of what makes them useful for teaching.
Singapore: Designing Nature into the City
Singapore is a small island nation with limited land, limited natural resources, and a dense and growing population. Despite these constraints, it has become internationally recognized for integrating ecological systems into urban infrastructure rather than treating them as competing interests.
Singapore’s “City in Nature” vision, launched in 2021, aims to create a green, liveable, and sustainable home for all citizens by 2030 — conserving and restoring nature, expanding community parks, and strengthening the connections between green spaces. The country’s four nature reserves serve as primary providers of ecosystem services, helping to clean air and water and support native flora and fauna. Nature parks were formed around these reserves specifically to buffer them from urbanization. Nearly half of Singapore is now green space, supported by 370 kilometers of park connectors that link parks and neighborhoods across the island.
These functions are sometimes described as ecosystem services — the measurable contributions that healthy natural systems make to human well-being. Singapore has invested in quantifying and protecting these services rather than assuming they will persist on their own. Singapore even developed its own City Biodiversity Index, a framework for evaluating urban biodiversity and ecosystem services that has since been implemented in cities globally.
For students, Singapore raises a foundational question: what would it look like to plan a city the way an ecologist thinks?
Medellín, Colombia: Equity and Green Infrastructure Together
Medellín was once one of the most violent cities in the world. Over the past two decades, it has become a global reference point for urban transformation — not only in terms of public safety but in terms of how infrastructure can address both environmental and social inequality at the same time.
In 2016, Medellín launched a green corridor project aimed at creating an interconnected 20-kilometer network of shade by transforming 18 roads and 12 waterways into green spaces. The results were measurable. Temperatures fell by 2°C in the first three years of the program , and officials expect a further decrease of 4–5° over the coming decades. Air quality also improved significantly: levels of particulate pollutants dropped, and in just one corridor, new vegetation was estimated to absorb over 160,000 kilograms of carbon dioxide per year.
The corridors were co-managed by community-based organizations, ensuring responsiveness to safety, cultural use, and public access. Green jobs were created for local residents trained in planting, maintenance, and environmental monitoring. Universities conducted air and temperature monitoring and fed that data into planning.
Medellín asks students an important question that Singapore does not always raise: who benefits from green infrastructure, and who is left out?
Curitiba, Brazil: Planning as Prevention
Curitiba is often cited as one of the most sustainably planned cities in the world, and its story is particularly instructive because its innovations were born of constraint rather than abundance.
Beginning in the 1960s under Mayor Jaime Lerner, Curitiba implemented strict land use controls, pedestrian-focused development, and an efficient bus rapid transit system that eventually came to serve 85% of residents. Rather than building expensive concrete drainage infrastructure to manage flooding, the city converted floodplains into parks and surrounded urban areas with grass fields, saving both cost and environmental impact. The cost of this approach has been estimated at 5% lower than building conventional concrete canals.
Today, Curitiba has 52 square meters of green space per person — one of the highest densities of urban green space in the world — and is known as the environmental capital of Brazil.
What Curitiba teaches is the value of upstream thinking: intervening early, designing for prevention rather than response, and treating ecological constraints as planning parameters rather than obstacles.
Houston, Texas: Learning from Failure
Houston is a different kind of case study — and a necessary one. When Hurricane Harvey hit in 2017, it dropped more rainfall on the Houston metropolitan area than any storm in US history. The flooding was catastrophic. More than 100,000 homes in the Houston area were damaged or destroyed by Harvey’s floodwaters.
The disaster was not simply a function of an unprecedented storm. Houston, the largest US city with no zoning laws, is a case study in limiting government regulation and favoring growth — often at the expense of the environment. Wetland loss is one of many effects of this approach; while vanished wetlands would not have prevented flooding entirely, experts say they would have made it significantly less severe.
The communities hit hardest were not random. Research shows that 30 to 50% of flooded properties would not have flooded without climate change, and that climate change-attributed impacts were particularly concentrated in low-income Latina/o neighborhoods, including many located outside of FEMA’s officially designated floodplains.
Houston has since invested in green stormwater infrastructure and bayou restoration. Local advocates now emphasize protecting coastal prairie wetlands as one of the region’s best defenses against flooding — a form of natural infrastructure that was largely paved over during decades of unregulated development.
Houston is valuable precisely because it is complicated. It shows students what happens when development outpaces planning, and it raises hard questions about accountability, equity, and what resilience actually requires.
New York City: Scale, Equity, and the Limits of Good Intentions
New York City has some of the most ambitious sustainability commitments of any city in the United States. Its green infrastructure programs, urban tree canopy initiatives, coastal resilience planning, and building decarbonization laws are among the most comprehensive in the country.
And yet the benefits are distributed unevenly. Majority Black and Brown neighborhoods in NYC have 33% less tree canopy on average than majority white communities. Low and moderate-income neighborhoods have 25% less canopy than higher-income areas. Neighborhoods with the highest poverty rates have 41% less tree coverage than the wealthiest neighborhoods.
Neighborhoods with less canopy — particularly in parts of the South Bronx and Central Brooklyn — experience higher surface temperatures, greater exposure to extreme heat, and elevated rates of heat-related illness.
Reaching citywide canopy goals without centering equity is possible — but experts note it would be “much simpler and probably a lot cheaper” to do it that way. True equity requires working with community members to understand their specific visions, and raises the additional concern of green gentrification, where new green spaces increase the cost of living and price lower-income residents out of their neighborhoods.
For students, New York offers a lesson about the gap between policy intention and lived reality. It raises questions about how environmental benefits are allocated, how community voice shapes planning decisions, and what it means to pursue sustainability in a city defined by deep inequality.
Three Frameworks for Teaching with These Cities
Ecosystem Services and Natural Capital
Each of these cities, in different ways, is grappling with the same underlying question: what does nature do for us, and what happens when we lose it?
Students can investigate this question by mapping ecosystem services in their own communities. What trees exist, and where are they? Where does stormwater go when it rains? What functions are missing — cooling, filtration, habitat, recreation — and where are those gaps most acute?
This kind of analysis does not require a construction budget. It requires observation, research, and systems thinking.
Systems Thinking
Environmental challenges rarely arrive alone. Rising temperatures, flooding, health disparities, and economic instability are connected through complex networks of cause and effect.
Teaching students to see these connections is one of the most durable things an educator can do. A systems map of urban heat, for example, might show how lack of tree cover increases surface temperature, which raises cooling costs, which strains household budgets, which affects health outcomes, which affects school attendance and economic productivity.
The cities above are rich with examples of these feedback loops — both the destructive ones that compound harm and the generative ones that can compound benefit when systems are redesigned well.
Design Thinking Applied to Local Conditions
None of the cities above succeeded by copying another city’s blueprint. Singapore’s solutions are specific to Singapore’s climate, scale, and governance. Curitiba’s approach was shaped by its particular moment and constraints. Medellín’s transformation is inseparable from its political history.
This is an important lesson for students: design is always contextual. The goal is not to replicate what worked elsewhere but to understand the principles well enough to apply them somewhere new.
A design-thinking unit might ask students to identify a problem in their own neighborhood — excessive heat, lack of green space, flooding, polluted waterways — and develop a proposal for addressing it. The cities in this piece become a library of strategies to draw from, not a single answer to copy.
Adapting Across Grade Levels
The concepts in this piece — ecosystem services, systems thinking, urban design, equity — scale across educational levels.
Younger students might begin with observation and mapping: drawing their block, counting trees, noticing where heat collects, asking where water goes when it rains. They might study one city and one big idea.
High school students can move into analysis: comparing cities, examining tradeoffs, investigating who benefits and who bears risk. They can begin to engage with data — heat maps, tree canopy surveys, flood zone records — and connect local conditions to larger patterns.
Undergraduate students can go deeper into policy, governance, and political economy: who decides how cities are planned, how funding flows, what makes some interventions stick and others fail. They can engage with primary sources, conduct original fieldwork, and develop substantive proposals.
The cities in this piece can serve any of these levels. What changes is the depth of analysis and the complexity of the questions asked.
Why This Matters
The careers of the future will increasingly require people who can think across disciplines — who can hold environmental, social, and economic considerations at the same time and work toward solutions that account for all of them. Urban planners, engineers, public health professionals, educators, policymakers, community organizers, and entrepreneurs all need this kind of thinking.
More fundamentally, students who understand how cities work — how they are designed, how they fail, and how they can be redesigned — are better equipped to participate in the decisions that will shape their own communities.
The cities in this piece are not finished projects. They are works in progress, full of contradictions and open questions. That is exactly what makes them worth studying.
The question worth putting to students is not “What is the answer?” It is: “If you were designing this, what would you do differently — and for whom?”
That is a question worth bringing into every classroom.
Sources
- World Economic Forum — Singapore’s City in Nature and nature-first urban planning: https://www.weforum.org/stories/2025/01/how-nature-first-master-planning-has-helped-these-cities-create-new-green-identities/
- National Parks Board Singapore — City in Nature key strategies: https://www.nparks.gov.sg/who-we-are/city-in-nature-key-strategies
- Socio.Health — City Biodiversity Index and urban planning: https://socio.health/ecology-environment-urban-development/city-biodiversity-index-urban-planning/
- Asia-Pacific Platform for Climate and Disaster Risk Reduction — Medellín green corridors: https://ap-plat.nies.go.jp/inas/goodpractices/development/5.html
- Reasons to Be Cheerful — Medellín green corridors and temperature reduction: https://reasonstobecheerful.world/green-corridors-medellin-colombia-urban-heat/
- The Dirt — Urban ecosystem services in Medellín: https://thedirt.news/urban-ecosystem-services-medellins-cooling-green-corridors/
- IHRB Just Stories — Medellín Corredores Verdes and social co-benefits: https://www.just-stories.org/database/cooling-streets-with-nature-based-solutions-and-social-co-benefits-colombias-medell%C3%ADn-green-corridors
- Scribd/Global Sustainable City Award — Curitiba sustainable urban development: https://www.scribd.com/document/436367790/Curitiba
- The Borgen Project — Sustainability in Curitiba: https://borgenproject.org/sustainability-in-curitiba/
- UN Sustainable Development Knowledge Platform — Curitiba urban planning: https://sustainabledevelopment.un.org/index.php?page=view&type=99&nr=57&menu=1449
- ASCE Civil Engineering — Curitiba master plan at 60 years: https://www.asce.org/publications-and-news/civil-engineering-source/civil-engineering-magazine/issues/magazine-issue/article/2025/07/brazils-curitiba-has-been-following-its-master-plan-for-60-years
- NPR — Houston flood damage after Hurricane Harvey: https://www.npr.org/transcripts/550757727
- Quartz — Houston development, wetland loss, and Hurricane Harvey: https://qz.com/1064364/hurricane-harvey-houstons-flooding-made-worse-by-unchecked-urban-development-and-wetland-destruction
- ScienceDirect — Environmental justice and Hurricane Harvey flooding: https://www.sciencedirect.com/science/article/abs/pii/S0013935119305699
- Bayou City Waterkeeper — Houston wetlands and flood resilience: https://bayoucitywaterkeeper.org/5-most-critical-wetland-areas-our-solution-to-flooding-has-always-been-here/
- NY League of Conservation Voters — NYC urban forest equity: https://www.nylcv.org/news/policy-means-people-nycs-urban-forest-plan/
- NYC Comptroller — NYC urban forest and tree canopy report: https://comptroller.nyc.gov/reports/new-york-citys-living-infrastructure-funding-and-managing-nycs-urban-forest-and-tree-canopy/
- Sierra Club — NYC canopy goals and green gentrification: https://www.sierraclub.org/sierra/new-plan-lays-out-path-boost-nyc-s-tree-canopy