Reading Standards for Informational Text > Author’s Craft: Structure and Time (CCSS.RI.7.2) Practice Test

Cooling the City: Facing Urban Heat

1 The Problem Cities are warming faster than nearby rural areas. Scientists use the term "urban heat island" to describe this pattern: paved streets, tall buildings, and dark roofs trap heat during the day and release it slowly at night. In some neighborhoods, afternoon temperatures run 5–7 degrees Fahrenheit higher than in surrounding towns. Emergency rooms report more heat-related illnesses during these spikes.

2 Why Cities Heat Up Heat builds for several reasons. First, asphalt and concrete absorb sunlight. Second, engines and air conditioners give off extra heat, a process called "anthropogenic warming." Third, cities often have fewer trees, so there is less shade and less cooling from evaporation. "Heat islands are a predictable result of design choices," says Dr. Lina Ortiz, an urban climate researcher. Her team measured a 30 percent tree-cover difference between neighborhoods only three miles apart.

3 Who Feels It Most The effects are not equal. A city health report found that lower-income areas recorded twice as many days above 95°F last summer. Many residents there also pay higher electricity bills, because older buildings lose cool air. One high school student described skipping afternoon practice when the blacktop field became too hot to touch. Heat can also slow learning; test scores dip slightly on very hot days, according to a statewide analysis of 200,000 exams.

4 What Can Help Cities are testing solutions. Planting street trees can lower local air temperatures by 2–4°F. Light-colored "cool roofs" reflect sunlight; one pilot spread reflective coating on 200 rooftops and cut indoor temperatures by up to 5°F. Pocket parks turn small, vacant lots into green spaces. These changes also reduce energy use. A city-wide program that added 10,000 trees reported a 6 percent drop in peak summer electricity demand. "Nature-based design is cost-effective and fast," says landscape architect Priya Nand. She notes that neighbors who help water new trees form networks that check on seniors during heat waves.

5 A Plan, Not a Patch Experts recommend mapping the hottest blocks, then investing first where risk is greatest. Public messages that define heat advisories and list cooling centers save lives. While no single step solves the problem, layering shade, reflective materials, and community support can make summers safer for everyone.

Letting Rivers Breathe: Rethinking Dams

1 What Dams Do Dams store water, generate electricity, and control floods. They also slow rivers, trapping sediment and blocking fish migration. The American Rivers group estimates more than 90,000 dams in the United States. "Barriers fragment habitats," explains fisheries biologist Dr. Gordon Lee. When salmon cannot reach spawning grounds, their numbers drop, and entire food webs feel the loss.

2 Weighing Costs Communities are examining aging structures. Some dams no longer produce much power; others are costly to maintain. A state report found that 1 in 7 inspected dams needed safety upgrades. Downstream, beaches shrink without fresh sediment. Local anglers report fewer catches than a generation ago, and water warms behind reservoirs, stressing cold-water species.

3 How Removal Helps Taking out a dam can reconnect miles of habitat in days. On Washington's Elwha River, two large dams were removed between 2011 and 2014. Within a year, scientists recorded salmon returning to tributaries they had not reached for a century. Sediment rushed downstream, rebuilding sandbars. "The river began to heal itself," said geomorphologist Maria Ortega, who mapped new channels after high flows.

4 Evidence and Expert Views Data show similar patterns elsewhere. A review of 137 U.S. removals found increases in fish diversity within five years. Water temperatures dropped in stretches that regained shade from recovering floodplain trees. "Restoration is not instant," Dr. Lee cautions, "but the trajectory is positive when barriers are gone and banks are stabilized."

5 Planning a Path Forward Removal is not always the answer. Some dams provide drinking water or critical power during heat waves. Engineers can add fish ladders or release cooler water at key times. Public meetings and cost studies help decide whether to remove, retrofit, or reinforce. The goal, experts say, is to restore river function while meeting community needs.