Learning target: I can work with a team to evaluate six real solutions to human pressures on ecosystems using scientific, economic and social criteria, and explain one solution on my own.
Directions
Work in home groups of three. Step 1, expert round (12 minutes): each member takes one expert set of four cards (Set A: cards 1-4; Set B: cards 5-8; Set C: cards 9-12), meets with students from other groups who hold the same set, and completes Part A. Step 2, home round (25 minutes): return to your home group, teach your two cases, and fill in the group table together. Step 3, ranking (8 minutes): agree on a ranking and answer q3 and q4. Step 4, individual (10 minutes): answer Part C alone, without help.
You will need: Twelve cards per home group, cut apart (or one printed card sheet per expert group), This worksheet, one per student, Pencils, Timer for the teacher
Twelve evidence cards: six pressures and six solutions
1 Card 1 (Set A): Over-exploitation problem, Lake MalawiAs the population along Lake Malawi in southeastern Africa grew, heavy fishing removed many small cichlid fish that eat snails. The snails carry the young stage of the parasite that causes bilharzia, a long-lasting disease. Studies comparing sites found fewer infected children where snail-eating fish were common. Most families depend on the lake for food and income.
2 Card 2 (Set A): Solution, larger-mesh netsNets with larger holes still catch big fish, but small snail-eaters slip through and survive. The nets are cheap, can be made from local materials, and let families keep fishing. Tradeoff: fewer fish in each haul at first. Evidence: the fish-and-infection link comes from comparing sites, not from a controlled test, so snails and infections must be tracked after the change.
3 Card 3 (Set A): Pollution problem, plastic in the oceanMillions of metric tons of plastic reach the ocean every year. Sea turtles mistake floating bags for jellyfish and swallow them, and lost nets and fishing line tangle turtles, seals and seabirds. Most plastic does not rot away; sunlight and waves break it into smaller and smaller pieces, and pieces under 5 millimeters are called microplastics.
4 Card 4 (Set A): Solution, using less plasticOptions include reusable bottles and bags, recycling, less packaging and new materials. California banned most single-use plastic carryout bags at large grocery and drug stores in a 2014 law that voters upheld in 2016. Limits: some alternatives cost shoppers or stores more, only a small share of plastic is recycled, and many plastics labeled 'biodegradable' break down only in industrial compost facilities, not in seawater.
5 Card 5 (Set B): Emerging disease problem, Nipah virusIn Malaysia in 1998 and 1999, a virus new to people spread from pig farms. Fruit bats naturally carry Nipah virus, usually without getting sick. On farms where pigs were kept near fruit trees that bats fed in, pigs ate fruit the bats had bitten or dropped, became infected and passed the virus to farmworkers. More than 100 people died.
6 Card 6 (Set B): Solution, keep bats and farm animals apartHealth agencies advise keeping pigs away from fruit trees where bats feed, covering feed and pig sheds, and wearing gloves and protective clothing when handling sick animals. Limits: moving pens or removing trees costs farmers money and space, workers need training and gear, and the virus stays in the bats. The bats are wild animals that pollinate fruit trees and spread seeds, so killing them would harm forests.
7 Card 7 (Set B): Habitat degradation problem, sun coffeeIn parts of Central and South America, forests are cleared to plant coffee in full sun. Black-and-white warblers and other songbirds that nest in North America spend the winter in these forests. Clearing removes the trees they feed and shelter in, along with the flowering plants that support bees and the roots that hold soil on steep slopes.
8 Card 8 (Set B): Solution, shade-grown coffeeCoffee can grow under taller trees that hold soil, shelter birds and support bees. Tradeoff: a shaded farm harvests fewer beans per hectare than a full-sun farm. Some buyers pay a higher price for certified bird-friendly coffee, but not every farm finds such a buyer. Shade farms help many birds, but some forest species still need real forest.
9 Card 9 (Set C): Invasive species problem, Asian carpSeveral carp species were brought to the United States from Asia in the 1960s and 1970s to control weeds and algae in fish farms and wastewater ponds. Some escaped during floods into the Mississippi River system. Silver and bighead carp eat huge amounts of plankton, the food that young native fish need, and have few predators here. They are moving upriver toward the Great Lakes.
10 Card 10 (Set C): Solution, electric barriersNear Chicago, electric barriers in a shipping canal that links the Mississippi River system to Lake Michigan send a pulsing current through the water that turns fish back while boats pass through. Limits: the barriers must run all the time and be maintained, they are costly, and they cannot remove carp already in the rivers. Agencies also net and fish out carp and test river water for carp DNA.
11 Card 11 (Set C): Climate change problem, rising seasSince 1880 the average height of the world's oceans has gone up about 21 to 24 centimeters, mainly because seawater expands as it warms and melting land ice adds water. Low-lying coastal places such as Miami Beach and parts of San Diego flood more often during storms and very high tides. Marshes and dunes drown or get squeezed between the rising water and roads or seawalls.
12 Card 12 (Set C): Solution, plan with modelsComputer models use past and present data to project a range of future sea levels. NOAA projects about 25 to 30 cm (10 to 12 inches) of rise along U.S. coasts between 2020 and 2050. Planners use the range to choose among seawalls, raised roads, restored marshes and dunes that absorb waves, or moving buildings back. Limits: projections further ahead are less certain, seawalls are costly and can wipe out the beach or marsh in front of them, and moving homes is hard on families.