HS-LS2-7: Designing Solutions to Protect Biodiversity
Also called NGSS HS-LS2-7 · Topic: Interdependent Relationships in Ecosystems · Life Science
The Official Wording
Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
Clarification statement: Examples of human activities can include urbanization, building dams, and dissemination of invasive species.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-LS2-7 Means in Plain English
High school students pick a way people harm ecosystems, such as a dam blocking migrating fish, a city paving over wetlands or an invasive plant crowding out native ones. They design a fix, judge it against clear criteria and costs, then test and improve it.
The work is an engineering cycle, so no single right answer exists, but every claim about a design must rest on evidence about the ecosystem. It builds on HS-LS2-6, how ecosystems respond to change, and pairs with HS-ETS1-3 on weighing tradeoffs.
HS-LS2-7 I Can Statements
- I can describe how a human activity harms an ecosystem.
- I can compare two designs using criteria, constraints and evidence.
- I can use test results to improve a solution.
HS-LS2-7 Worked Example
A design challenge built around a model dam in a rain gutter, where students test whether fish could get past it.
Which fish passage design slows the water enough for fish to swim past a dam?
Set It Up: A 3-meter vinyl rain gutter tilted on books, a plastic block dam, a garden hose on low, a cork, a stopwatch and craft sticks for building steps.
- Define the problem: salmon can swim up gentle currents but not a steep, fast chute around a dam.Criterion: slow water on every stretch. Constraint: 20 craft sticks
- Build design A, a smooth ramp around the dam, and time the cork over one meter.Ramp: 1.2 seconds per meter, about 0.8 m/s
- Build design B, a ladder of small pools separated by craft-stick weirs, and time the cork again.Pools: 3.5 seconds per meter, about 0.3 m/s
- Run each design three times and average the times.Pools stay slowest in all three runs
- Refine design B by adding two more weirs on the steepest stretch and retest.Steep stretch drops from 0.5 to 0.3 m/s
The pool-and-weir ladder kept the current slowest, and adding weirs where the slope was steepest improved it further.
Why it works: Each small drop into a pool spends the water's energy in swirling, so fish face short bursts of fast water with calm pools to rest in, which is how real fish ladders work.
Common Mistakes with HS-LS2-7
Solving only the human side
“Just tear the dam down” with no thought about power or flood control
Try this: List what people need from the dam as constraints, then look for designs that protect the fish while still meeting those needs.
Declaring a winner without tests
“The ladder looks better, so it wins”
Try this: Decide on measurable criteria first, like water speed or cost, and collect data on every design before choosing which one to improve.
Stopping after the first build
One test, then straight to the write-up
Try this: Treat the first result as a starting point: find the weakest part of the design, change it, and test again to show improvement.
Where HS-LS2-7 Fits
Practice HS-LS2-7
Quick Check
- A town plans a dam on a river where salmon migrate. Name one design that could reduce the harm.
- Why set criteria before testing designs?
- An invasive plant is spreading along a creek. Why might pulling it out once fail?