South Dakota Science HS-LS2-6
The Standard
Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms under stable conditions; however, moderate to extreme fluctuations in conditions may result in new ecosystems. (SEP: 7; DCI: LS2.C; CCC: Stability/Change)
South Dakota Science Standards (2024) · Ecosystems: Interactions, Energy, and Dynamics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students compare species counts and environmental records across several years. They judge whether the evidence and food-web reasoning support a claim of stability, recovery, or lasting change.
What Mastery Looks Like
- A student can identify the usual range of species counts during stable years and compare it with counts after a disturbance. They explain a possible food-web link and flag when the record is too short to rule out recovery.
Common Misconceptions
- Students may treat any drop in a population as proof of a new ecosystem, even when counts rebound. They may think stable means identical counts every year, or blame a drought without checking other causes.
How to Assess It
- Exit ticket: Pond fish counts were 50, 48, 52 before a drought and 12, 10, 11 over the next three years; frog counts went from 20, 21, 19 to 35, 33, 36. Does this prove a new ecosystem formed? Cite two counts and name one other piece of evidence you need.
Lesson moves
Ways to Teach It
Connect pond organism cards with yarn, remove a plant card, and use sticky notes to mark which populations might change.
Give students pond counts from three years before and after a drought; ask which claim fits and what evidence is missing.
Play claim-evidence match with species counts, rainfall, and food-web cards; reject claims that treat one bad year as permanent change.
Read a news report on a lake fish kill; list the monitoring data needed to tell recovery from lasting change.
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Printable HS-LS2-6 Worksheet
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Related Standards
- MS-LS2-4
Construct an evidence-based argument that articulates how changes to physical or biological components of an ecosystem affect populations.
- 3-LS4-4
Make an evidence-based claim about the validity of a solution to a change in the environment that affects the types of plants and animals that live there.
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