Life Science · California Grade 7

MS-LS2-4

Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.

Clarification statement: Emphasis is on recognizing patterns in data and making warranted inferences about changes in populations, and on evaluating empirical evidence supporting arguments about changes to ecosystems.

Source: California Department of Education, NGSS Preferred Integrated Course Model, Grade 7 (accessed 2026-10-18)

Chapters

Chapter 6: Food Webs and Trophic Pyramidspractice

Students predict direct and indirect effects of removing or adding a population (Lab 1, W6, W9) and judge whether a lake intervention worked from monitoring data (Lab 3, slide 21). The evidence is model-based or simulated rather than empirical field data, so the role is practice toward constructing an evidence-based argument.

Chapter 20: Resources in Living Systemspractice

In Lab 3 students argue from simulated data that adding cattle to a range changed the deer population, and must separate the cattle effect from rainfall, recovery lag, water, predators and counting error. This is practice for the evidence-based argument the PE requires; Lesson 22 assesses it with real ecosystem changes.

Chapter 22: Changing Ecosystemsassesses

This is the chapter's performance expectation. Students construct arguments supported by empirical evidence in Lab 3 (their own pooled disturbed-versus-undisturbed plot data), the Lab 2 closing argument (real survey counts of burrowing owls on active and inactive prairie dog colonies), W6 (a CER from with-and-without and before-and-after plot data), the W8 individual argument from published prairie dog findings, and W10 items 9 and 12. W5 and the slide 20 task practice reading the same kinds of data, and Lab 1 and the Lab 2 string-web trials practice the reasoning with observation cards and a model before students use measured data.

Chapter 27: Biodiversitypractice

Students argue from their own quadrat data that mowing changes which plants grow (Lab 1) and from survey data that losing urchin predators changed many populations in one kelp cove (Lab 2). Lab 1's evidence is empirical but small and confounded, and Lab 2's is simulated, so the chapter builds this Grade 7 practice rather than assessing the full PE.

Worksheets (32)

Chapter	Worksheet	Role	How it connects
Ch. 6	W3 · The Otter, the Urchin and the Kelp: Reading a Food Web from the Top Down Reading with evidence	supports	The island comparison in the passage is a real example of empirical evidence that removing a biological component changes other populations; students read and evaluate the evidence rather than constructing the argument themselves.
Ch. 6	W6 · When the Coyotes Left: A Claim-Evidence-Reasoning Case Claim, evidence, reasoning	practice	Students construct an argument from patterns in population data that a change to a biological component (removing coyotes) affected other populations. The data are simulated, so this builds the practice rather than producing evidence with real empirical data.
Ch. 6	W8 · Bear Creek Jigsaw: Twelve Cards, One Stream Food Web Collaborative investigation	practice	The disturbance round asks teams to predict and justify population changes after a change to the ecosystem, building the reasoning they will need to argue from data about such changes.
Ch. 6	W10 · Food Webs and Trophic Pyramids: Mastery Check Retrieval and mastery check	practice	Two items ask students to predict population changes from a stated food web; they practice the reasoning behind arguments about changes to ecosystems without analyzing empirical data.
Ch. 7	W1 · Two Ponds, One Rainstorm: Why Did Only One Turn Green? Phenomenon exploration	supports	The dead fish at the end of the story hint that a change to a nonliving part of the pond (added nitrate) changed a population. That idea is background here and is developed in Worksheets 5 and 8.
Ch. 7	W3 · The Air Is Full of Nitrogen, and Almost Nobody Can Eat It Reading with evidence	supports	The final paragraphs describe how a change to a nonliving part of a water ecosystem (extra nitrate) led to a fish die-off. This is background for the evidence argument students build in Worksheet 8.
Ch. 7	W5 · Carbon by the Hour, Nitrogen by the Week: Two Teaching Datasets Data and graphing	practice	The pond data show a change to a nonliving component (nitrate) followed by a change in a population (algae cover). Reading that pattern builds the data-analysis practice the PE calls for, though students do not yet write the full argument.
Ch. 7	W8 · Who Turned Miller Pond Green? An Evidence Jigsaw Collaborative investigation	practice	Students argue from measurements (nitrate, oxygen, algae cover, fish deaths) that a change to a nonliving component affected populations. The argument is built collaboratively from cards, so it is practice toward the PE rather than individual evidence of meeting it.
Ch. 20	W3 · Twenty-Nine Reindeer: Boom and Crash on St. Matthew Island Reading with evidence	supports	The reindeer's grazing changed the island's lichen cover, a biological component, and that change affected the population. Students read about this chain here; they argue from it later in the chapter.
Ch. 20	W6 · What Limits the Water Fleas? A Claim-Evidence-Reasoning Case Claim, evidence, reasoning	practice	The CER asks for an argument from empirical evidence that a change to a component of the jar ecosystem (the food supply) changed the population. It builds the argumentation practice this PE assesses.
Ch. 22	W1 · Gray to Green: What Happened at Mount St. Helens After 1980? Phenomenon exploration	practice	Students begin noticing that a physical change (an eruption that buried the land) reshaped which populations lived there, and start asking what evidence would show how populations came back. This is the opening move toward building an argument from evidence.
Ch. 22	W2 · Words for a Changing Place: Succession, Disturbance and Resilience Vocabulary in action	supports	Students need precise words (physical component, biological component, disturbance, succession, evidence) before they can build an argument that changes to those components affect populations. This sheet builds that vocabulary through sorting and application rather than memorizing definitions.
Ch. 22	W3 · Survivors and Newcomers: How Mount St. Helens Came Back Reading with evidence	practice	The passage reports what scientists measured at fixed plots over decades, and the questions ask students to use those measurements as evidence that a physical change (burial under pumice and ash) shaped which populations returned and how fast. This builds the evidence-citing habit the PE requires.
Ch. 22	W4 · Reading a Succession Model, Then Building Your Own Diagrams and models	practice	Students read models that connect a physical change (fire, lava) to the sequence of populations that follow, and then construct their own. Modeling the chain from a changed component to shifting populations builds toward arguing about it with evidence.
Ch. 22	W5 · With and Without Beavers: What the Stream Surveys Show Data and graphing	practice	Students analyze with-and-without and before-and-after stream data showing that a change to physical components (water depth and speed behind a beaver dam) shifted three populations, and they write a claim the data support. They do not yet build the full written argument with reasoning, which comes in W6, so the role is practice.
Ch. 22	W6 · Did the Lupine Change the Pumice Plain? A Claim-Evidence-Reasoning Case Claim, evidence, reasoning	assesses	Students write a complete claim-evidence-reasoning argument from repeated, comparative plot data, using a baseline year and a lupine-free comparison group to rule out another explanation. That is the argument from empirical evidence the PE asks for, and the rubric scores it directly.
Ch. 22	W7 · Fixing Jordan's Argument About the Pine Creek Dam Error analysis	practice	Students judge whether a two-year before-and-after comparison supports a cause, bring in a comparison stream and more years, and rewrite the argument with a mechanism. Evaluating the evidence behind an argument builds directly toward the PE; the full argument is assessed in W6.
Ch. 22	W8 · Prairie Dog Evidence Sort: Who Gains, Who Loses, and How Do We Know? Collaborative investigation	assesses	The clarification statement emphasizes evaluating empirical evidence about changes to ecosystems. Groups rank published studies, teaching data, single observations and opinions, and each student then writes an argument, backed by the strongest cards, that removing a biological component (prairie dogs) changes other populations. The individual argument is scored with the rubric.
Ch. 22	W9 · Bringing Back Arroyo Verde: Design a Creek Restoration Transfer and design	practice	Students predict how the physical changes in their design (shade, still pools, removing an invasive plant) will shift populations, and plan the before-and-after and with-and-without measurements that would supply empirical evidence for those predictions.
Ch. 22	W10 · Changing Ecosystems: Mastery Check Retrieval and mastery check	assesses	Item 9 asks students to judge which empirical evidence best supports a claim about a population, and item 12 asks for a short argument, with evidence from the eruption, that a change to physical components (burial under pumice versus ash over surviving soil) shaped which populations returned and how fast. The other items check the ideas that argument rests on.
Ch. 27	W1 · From 51 Birds to 325: The Parrot That Almost Vanished Phenomenon exploration	practice	Students use real population counts and a timeline to start an argument that changes to the biological parts of an ecosystem (introduced predators, cleared forest) changed a population. It is a first draft, not yet a full evidence-based argument.
Ch. 27	W2 · Variety and Loss: Sorting and Using the Language of Biodiversity Vocabulary in action	supports	Terms such as extirpation, habitat fragmentation and invasive species name the changes to ecosystem components that later arguments in the chapter connect to population changes.
Ch. 27	W3 · Three Kinds of Variety: Reading About Genes, Species and Ecosystems Reading with evidence	practice	Students cite evidence that changes to physical components (drained wetlands, freeways) and biological components (invasive iceplant and Argentine ants) of ecosystems change populations, practicing the evidence-based argument the PE calls for.
Ch. 27	W4 · Patches and Passages: Modeling Habitat Loss and Fragmentation Diagrams and models	practice	Students use a model to predict how a physical change to an ecosystem (houses, farms and a freeway replacing habitat) changes which populations can persist, and they separate two causes, habitat loss and fragmentation, with evidence from the model.
Ch. 27	W5 · Counting Dune Plants: Richness, Evenness and a Diversity Index Data and graphing	practice	Students analyze sample data to describe how a change to a biological component of an ecosystem (an invasive plant spreading) goes with changes in native plant populations, and they identify what the data cannot yet prove, practicing the empirical reasoning the PE asks for.
Ch. 27	W6 · Ants, Lizards and the Edge of Town: An Invasive Species CER Claim, evidence, reasoning	practice	Students construct a written argument from field and feeding-trial data that a change to a biological component of an ecosystem (an invasive ant) changed populations of native ants and of a predator that depends on them, the central practice of the PE. The data are simulated, so this is practice rather than an assessment of real empirical evidence.
Ch. 27	W7 · Fixing Talia's Field Report: Counting, Calculating and Naming Biodiversity Error analysis	practice	Statement 7 asks students to explain how a physical change (a freeway) affects a population's genetic diversity, and the corrections require using data rather than impressions, both part of arguing that ecosystem changes affect populations.
Ch. 27	W8 · The Island Fox Jigsaw: Twelve Cards, Five Solutions, One Recovery Collaborative investigation	practice	Teams build an evidence-based causal chain showing how changes to biological components (feral pigs, the loss of bald eagles, arriving golden eagles) changed the fox population.
Ch. 27	W10 · Biodiversity Mastery Check: Variety, Threats and Solutions Retrieval and mastery check	practice	Items 7, 9 and 11 ask students to explain, with a model or evidence, how a change to an ecosystem component (fragmentation, an invasive species, habitat loss) changes populations.
Ch. 28	W3 · The Cleanup Crew: What India Learned When Its Vultures Vanished Reading with evidence	practice	Students trace how a change to one biological component (vultures) affected other populations (feral dogs, rats) and judge which evidence supports a causal argument, the reasoning this PE asks for. The evidence comes from a passage rather than data students analyze themselves, so this is practice.
Ch. 28	W7 · Fixing Priya's Report on Nature's Services Error analysis	practice	Statement 5 overclaims cause from a correlation between two populations; students explain what evidence an argument about changes to an ecosystem would need.
Ch. 28	W10 · Healthy Ecosystems and the Services They Provide: Mastery Check Retrieval and mastery check	practice	q6 and q10 check whether students can trace an effect of losing one population on others and recognize the evidence needed to argue for cause rather than pattern.

Labs (9)

Chapter	Lab	Role	How it connects
Ch. 6	Lab 1 · Build the Web, Then Break It: A Model of an Oak Woodland Collaborative systems modeling	practice	Groups remove or boost one population and reason through direct and indirect effects with sign chains, which builds the cause-and-effect reasoning the PE's arguments require; the evidence here is the model, not field data.
Ch. 6	Lab 3 · Fixing Lake Vesipuro: Test a Restoration Plan on Paper Data-driven decision	practice	The decision must be justified with model output and the baseline data, tracing how removing or adding fish populations changes zooplankton, algae and clarity; the evidence is simulated, so this is practice toward the PE.
Ch. 7	Lab 3 · Feed the Field, Keep the Pond: Choosing a Fertilizer Plan Data-driven decision	supports	The dataset shows algae rising and dawn oxygen falling as pond nitrate rises; students read that pattern as background to the decision rather than constructing a full argument about population change.
Ch. 20	Lab 3 · The Cedar Hollow Case File: Deer, Cattle and the Next Dry Year Data-driven decision	practice	Students argue from patterns in the data that a new competitor lowered the deer herd's carrying capacity, and must rule out rainfall, recovery lag, water, predators and counting error. This practices the evidence-based argument the PE requires; Lesson 22 assesses it with real ecosystem changes.
Ch. 22	Lab 1 · The Mixed-Up Field Notebooks: Two Zones, One Eruption Evidence-based mystery	practice	Students build an argument from observation cards and a plant-cover dataset that the ground the eruption left shaped how fast plant and animal populations came back. Because the cards are summaries and the cover numbers are simulated, the lab practices the argument; Lab 3 produces the empirical evidence.
Ch. 22	Lab 2 · Pull One Thread: Testing a Prairie Web for Its Keystone Collaborative systems modeling	assesses	Students first practice tracing how a change to a biological component (a species removed) or a physical component (less soil water) shifts populations in a model. They then construct a short argument from published survey data that the loss of prairie dogs affected burrowing owl populations, which is an argument supported by empirical evidence as the PE requires.
Ch. 22	Lab 3 · Path or No Path? A Disturbed-Versus-Undisturbed Plot Survey Classroom field investigation	assesses	Students construct an argument from empirical evidence they collected themselves: paired-plot counts and soak times, pooled across the class, showing that trampling changed a physical component (soil compaction) and the plant and animal populations living in the plots. This is the chapter's main evidence for the PE.
Ch. 27	Lab 1 · Count the Kinds: Measuring Schoolyard Biodiversity with Quadrats Classroom field investigation	practice	Students collect their own field data and argue whether mowing changes which plants grow and how evenly they are mixed (q8). The data are real but come from two patches that differ in more than mowing and from a small sample, so the lab builds the argument practice rather than assessing the full Grade 7 PE.
Ch. 27	Lab 2 · Case File: Two Kelp Coves, One Heat Wave Evidence-based mystery	practice	Students argue from survey data and clue cards that a warmer ocean (physical) and the loss of urchin predators (biological) changed urchin, kelp, abalone and community-wide species numbers, and they rule competing explanations in or out. The data are simulated, so this builds the Grade 7 argument practice rather than assessing the PE with empirical evidence.