HS-LS2-2: Using Data to Explain Biodiversity and Populations
Also called NGSS HS-LS2-2 · Topic: Interdependent Relationships in Ecosystems · Life Science
The Official Wording
Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.
Clarification statement: Examples of mathematical representations include finding the average, determining trends, and using graphical comparisons of multiple sets of data.
Assessment boundary: Assessment is limited to provided data.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-LS2-2 Means in Plain English
Students use math such as averages, trends and side-by-side graphs to support explanations of why the number of species or the size of a population changes. They revise their explanations as new data comes in, from a schoolyard plot up to a whole rainforest.
On tests, students work from data sets they are given rather than collecting their own. It builds on HS-LS2-1 and leads to HS-LS2-7, where students design solutions that reduce human harm to biodiversity.
HS-LS2-2 I Can Statements
- I can calculate an average from repeated samples.
- I can compare biodiversity in two habitats using a graph.
- I can revise an explanation when new data disagrees with it.
HS-LS2-2 Worked Example
A Berlese funnel pulls tiny animals out of leaf litter, giving each lab group real counts to average and compare.
Does leaf litter from a wooded area hold more kinds of soil animals than mulch from a school flower bed?
Set It Up: Plastic funnels lined with window screen over cups of rubbing alcohol, desk lamps, bags of woodland leaf litter and flower-bed mulch, and magnifiers.
- Fill three funnels with woodland litter and three with mulch, the same volume each.Six samples, 500 mL each
- Leave the lamps on over the funnels for two days.Animals crawl down into the cups
- Sort and count the animals by type under magnifiers.Springtails, mites, beetle larvae, centipedes
- Average the number of kinds per funnel for each habitat.Woodland: 7 kinds. Mulch: 3 kinds
- Graph both averages with the range of the three samples.The ranges do not overlap
The woodland litter held more than twice as many kinds of animals on average, and its three samples agreed.
Why it works: Deep, varied litter offers more food, moisture and hiding places, so it supports more species than a thin layer of uniform mulch.
Common Mistakes with HS-LS2-2
Trusting one sample
“Our one mulch funnel had a centipede, so mulch is just as diverse”
Try this: Run several samples per habitat and compare averages and ranges. One sample can be unusual by chance.
Counting individuals instead of kinds
Calling a cup with 200 springtails the most diverse
Try this: Biodiversity includes how many kinds there are and how evenly they are spread, not just the total number of animals.
Sticking with the first explanation
“We already said mulch wins, so we left out the other groups' data”
Try this: Pool every group's data and let the pattern decide. A good explanation changes when the evidence points another way.
Where HS-LS2-2 Fits
Practice HS-LS2-2
Quick Check
- Three samples found 6, 8 and 7 kinds. What is the average?
- Habitat A has 100 ants. Habitat B has 30 ants, 30 beetles and 40 spiders. Which is more diverse?
- A new sample disagrees with your explanation. What should you do?