HS-LS4-6: Simulating Ways to Protect Biodiversity
Also called NGSS HS-LS4-6 · Topic: Interdependent Relationships in Ecosystems · Life Science
The Official Wording
Create or revise a simulation to test a solution to mitigate adverse impacts of human activity on biodiversity.
Clarification statement: Emphasis is on testing solutions for a proposed problem related to threatened or endangered species, or to genetic variation of organisms for multiple species.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-LS4-6 Means in Plain English
Students build or improve a computer simulation, often a spreadsheet, that tests a plan to help a species threatened by people. They set up the model, run it with and without the solution, and compare what happens to the population or its genetic variety over many years.
A model is only as good as its assumptions, so students state them, check them against real data where they can, and revise. This work draws on HS-LS2-7, where students design such solutions, and on HS-ETS1-4, which uses simulations to compare designs.
HS-LS4-6 I Can Statements
- I can build a simple simulation of a population over time.
- I can test a conservation solution by changing one model input.
- I can revise a model when its assumptions do not match data.
HS-LS4-6 Worked Example
A spreadsheet model of spotted salamanders that must cross a busy road each spring to reach their breeding pond.
Would a tunnel under the road keep a spotted salamander population from shrinking?
Set It Up: A spreadsheet with one row per year, starting with 400 adults, and a laptop for each pair of students.
- Set yearly rates: new adults join at 30%, 20% die naturally and 15% are killed by cars while crossing.Net change: 30% − 20% − 15% = −5% a year
- Fill the formula down 20 rows to run 20 years with no tunnel.400 adults fall to about 140
- Model the tunnel by cutting road deaths to 3%, since drift fences guide most animals into it.Net change: +7% a year
- Run 20 years again and notice the population grows without limit.Over 1,500 adults, more than the pond can hold
- Revise the model with a cap of 600 adults set by the pond's size, and rerun.Levels off at 600 within about 6 years
Without the tunnel the population shrank by about two thirds in 20 years, and with it the population grew until the pond's size limited it.
Why it works: Small yearly losses compound, so removing one cause of death can turn a shrinking population into a growing one, while habitat size still sets an upper limit.
Common Mistakes with HS-LS4-6
Treating the output as fact
“The spreadsheet proves the tunnel will save them”
Try this: Call the result a prediction that depends on the model's assumptions, and say which real data would confirm or overturn it.
Changing several inputs at once
Tunnel, more births and fewer natural deaths in one run
Try this: Change only the input the solution affects, keep every other value the same, and compare that run with the baseline.
No limit on growth
A population that climbs forever
Try this: Add a cap or slowing growth term for limited habitat, because real populations level off when food or space runs short.
Where HS-LS4-6 Fits
Practice HS-LS4-6
Quick Check
- Why compare the tunnel run with a run that has no tunnel?
- A model predicts endless growth. What is wrong?
- Why might a tiny population fail even if road deaths stop?