HS-LS2-6

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Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem.

Clarification statement: Examples of changes in ecosystem conditions could include ecological succession, modest biological or physical changes, such as moderate hunting or seasonal floods; and extreme changes, such as volcanic eruption or sea level rise.

Performance Level Descriptions

PLDs communicate the knowledge and skills expected of students to demonstrate proficiency in each Learning Standard. NYS assessments classify student performance into one of five levels.

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Level 1: Identify the evidence, from those provided, that supports the claim that complex interactions in an ecosystem maintain relatively consistent numbers and/or types of organisms in stable conditions.

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Level 2: Identify an evidence-based claim that the complex interactions in an ecosystem maintain relatively consistent numbers and types of organisms in stable conditions or that changing conditions may result in a new ecosystem or given evidence, from those provided, identify the claim that describes the complex interactions.

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Level 3: Evaluate a claim using evidence that the complex interactions in an ecosystem maintain relatively consistent numbers and types of organisms in stable conditions or that changing conditions may result in a new ecosystem.

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Level 4: Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions but changing conditions may result in a new ecosystem.

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Level 5: Use claims, evidence, and reasoning, to argue the merits of explanations regarding complex interactions in ecosystems and their ability to maintain relatively consistent numbers and types of organisms in stable conditions but changing conditions may result in a new ecosystem.

Resources

Examples and discussion of resources for the learning, teaching, and assessment of HS-LS2-6.

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Assessment

What assessment of HS-LS2-6 might look like on a NY state exam.

Exam	Cluster	Question
August 2026	Deep-Sea Dilemmas	Question 7
	Invasive Mussels	Question 37
	Parrots and Biodiversity	Question 40
June 2026	Nitrogen: Friend or Foe?	Question 8
	Green and Black Frogs	Question 13
	The Forest Gardener	Question 36
January 2026	Keystone Species Rule	Question 10
August 2025	Ivory and Elephants	Question 18
June 2025	Salt Marsh Shoreline	Question 22
	Salt Marsh Shoreline	Question 24
	Salt Marsh Shoreline	Question 26
	Keystone Species: Black-Tailed Prairie Dogs	Question 39
Sample clusters (Spring 2024)	Coral Reefs	Question 1
	Dinosaurs-Evolution	Question 3

NGSS Dimensions

Performance expectation HS-LS2-6 was developed using the following elements from the NRC document A Framework for K-12 Science Education:

Science and Engineering Practices

• Engaging in Argument from Evidence: Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments.
• Scientific Knowledge is Open to Revision in Light of New Evidence
  • Scientific argumentation is a mode of logical discourse used to clarify the strength of relationships between ideas and evidence that may result in revision of an explanation.

Disciplinary Core Ideas

• LS2.C: Ecosystem Dynamics, Functioning, and Resilience
  • A complex set of interactions within an ecosystem can keep its numbers and types of organisms relatively constant over long periods of time under stable conditions. If a modest biological or physical disturbance to an ecosystem occurs, it may return to its more or less original status (i.e., the ecosystem is resilient), as opposed to becoming a very different ecosystem. Extreme fluctuations in conditions or the size of any population, however, can challenge the functioning of ecosystems in terms of resources and habitat availability.

Crosscutting Concepts

• Stability and Change
  • Much of science deals with constructing explanations of how things change and how they remain stable.

Page contributors: Conrad Richman, Caroline Leonard

Biology | HS. Interdependent Relationships in Ecosystems