1. US Curriculums
  2. NGSS
  3. Grade 7
  4. Science
  5. Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations

Grade 7 · Science

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

Quarter 2 · Week 7 · NGSS

Standards Alignment

  • MS-LS2-4 primary
    Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.

Companion Video Lesson

This text lesson has a separate video watch page so search engines and learners can treat the written lesson and the video lesson as distinct resources.

Open the dedicated video lesson page

Lesson Overview

In this Grade 7 science lesson, students will learn how to construct scientific arguments supported by empirical evidence to explain how changes to physical or biological components of an ecosystem affect populations. Through investigation, data analysis, and model building, students will explore ecosystem dynamics and develop reasoning skills aligned with NGSS standard MS-LS2-4.

Learning Objectives

  • Explain how changes to physical or biological components of an ecosystem can affect populations.
  • Analyze empirical evidence to support claims about ecosystem changes and their effects on populations.
  • Construct oral and written scientific arguments using evidence and reasoning.
  • Develop and revise models to represent ecosystem dynamics and population changes.

Success Criteria

  • Students can identify physical and biological components of an ecosystem and describe how changes impact populations.
  • Students use data or observations to support claims about ecosystem changes.
  • Students construct clear arguments that link evidence to claims about population effects.
  • Students revise their arguments or models based on new evidence or peer feedback.

Prerequisite Knowledge

Students should understand basic ecosystem components, including populations, physical environment, and biological factors. They should be familiar with the concept of empirical evidence as observations or data collected through investigation. Prior experience with constructing explanations or arguments in science will support learning.

Key Vocabulary

  • Ecosystem
  • Population
  • Physical component
  • Biological component
  • Empirical evidence
  • Argument
  • Claim
  • Reasoning
  • Model
  • Ecosystem dynamics

Materials and Resources

  • Ecosystem case study data sets (e.g., graphs, tables, or descriptions of changes in an ecosystem)
  • Chart paper or whiteboard for argument mapping
  • Access to ecosystem simulation tools or videos (optional)
  • Science notebooks or writing paper
  • Markers or pens

Teacher Preparation

  • Prepare or select a case study showing a change in an ecosystem (e.g., introduction of an invasive species, drought, pollution) with associated data.
  • Review examples of scientific arguments and how to link claims with evidence and reasoning.
  • Set up materials for group work and presentations.
  • Prepare guiding questions to support student reasoning and argument construction.

Detailed Lesson Notes

Understanding Ecosystems and Their Components

An ecosystem consists of living (biological) and nonliving (physical) components interacting in a particular environment. Biological components include populations of plants, animals, and microorganisms. Physical components include factors like water availability, temperature, soil, and sunlight. These components are interconnected, and changes in one part can affect others. For example, a drought (physical change) can reduce water availability, affecting plant populations, which in turn affects animals that depend on those plants.

Ecosystem Dynamics and Population Changes

Ecosystems are dynamic, meaning their characteristics and populations can change over time. Disruptions to physical or biological components can cause shifts in population sizes. For instance, if a new predator is introduced (biological change), prey populations may decrease. Alternatively, pollution (physical change) can harm organisms, reducing their numbers. Understanding these cause-and-effect relationships is key to explaining ecosystem changes.

Empirical Evidence in Science

Empirical evidence is information gathered through observation or experimentation. In ecosystem studies, this might include population counts, measurements of environmental factors, or recorded changes over time. Scientific arguments rely on this evidence to support claims. For example, data showing a decline in a fish population after water pollution provides evidence that pollution affects that population.

Constructing Scientific Arguments

A scientific argument includes a claim (a statement about a phenomenon), evidence (data or observations supporting the claim), and reasoning (the explanation linking evidence to the claim). Students should learn to clearly state their claim about how an ecosystem change affects populations, support it with empirical evidence, and explain why the evidence supports the claim based on scientific principles.

Modeling Ecosystem Changes

Models help visualize and explain ecosystem dynamics. Students can create diagrams or use simulations to represent how changes to physical or biological components influence populations. Models can be revised as new evidence emerges, reflecting the dynamic nature of ecosystems and scientific understanding. For example, a model might show how decreased rainfall leads to lower plant growth, which reduces herbivore populations.

Worked Examples

Worked Example 1

Scenario

Given data showing a decrease in a frog population after a chemical spill in a pond, construct a scientific argument explaining the population change.

Explanation

The claim is that the chemical spill caused the decrease in the frog population. Evidence includes the timing of the spill and observed population decline. Reasoning explains that chemicals can be toxic to amphibians, affecting survival and reproduction, leading to fewer frogs.

Answer Guide

The chemical spill caused the frog population to decrease. Data shows the population dropped after the spill occurred. Chemicals in the water likely harmed the frogs, reducing their numbers because they are sensitive to pollutants.

Engage

Teacher Activity

Introduce a real-world example of an ecosystem change, such as the introduction of an invasive species or a drought event. Show images or a short video to capture interest.

Student Activity

Discuss initial thoughts about how such changes might affect populations in the ecosystem. Share any prior knowledge or experiences related to ecosystem changes.

Explanation

This phase activates students' prior knowledge and curiosity about ecosystems and sets the stage for investigating cause-and-effect relationships.

Examples

  • Students mention living and nonliving parts of ecosystems.
  • Students suggest possible effects of changes, such as population increases or decreases.
  • Students share examples from personal experience or media.

Explore

Teacher Activity

Provide students with data sets or descriptions from a case study showing changes in an ecosystem's physical or biological components and corresponding population data.

Student Activity

In groups, analyze the data to identify patterns or changes in populations related to ecosystem changes. Record observations and questions.

Explanation

Students gather and interpret empirical evidence to understand the effects of ecosystem changes on populations.

Examples

  • Students identify correlations between ecosystem changes and population shifts.
  • Students note specific data points or trends supporting their observations.
  • Students generate questions about cause and effect.

Explain

Teacher Activity

Guide students to construct scientific arguments using their data analysis. Model how to state a claim, cite evidence, and provide reasoning.

Student Activity

Develop oral or written arguments explaining how the ecosystem changes affected populations, using evidence from their analysis.

Explanation

Students practice constructing arguments that connect empirical evidence to claims about ecosystem dynamics.

Examples

  • Students clearly state claims about population effects.
  • Students cite specific data as evidence.
  • Students explain reasoning linking evidence to claims.
  • Students consider and address alternative explanations.

Elaborate

Teacher Activity

Challenge students to revise their arguments or models based on peer feedback or additional data. Facilitate discussion on ecosystem resilience and complexity.

Student Activity

Refine arguments or models to incorporate new evidence or reasoning. Discuss how ecosystems can recover or continue to change over time.

Explanation

Students deepen understanding by revising explanations and considering ecosystem dynamics beyond initial observations.

Examples

  • Students update claims and reasoning with new evidence.
  • Models become more detailed or accurate.
  • Students discuss ecosystem recovery and complexity.

Evaluate

Teacher Activity

Assess students' ability to construct arguments supported by empirical evidence through presentations, written reports, or discussions.

Student Activity

Present or submit scientific arguments explaining how changes to ecosystem components affect populations.

Explanation

Evaluation focuses on students' mastery of constructing evidence-based scientific arguments aligned with MS-LS2-4.

Examples

  • Students present coherent, evidence-based arguments.
  • Students demonstrate understanding of ecosystem dynamics.
  • Students use scientific vocabulary and reasoning effectively.

Classroom Activity

In groups, analyze the data to identify patterns or changes in populations related to ecosystem changes. Record observations and questions.

Guided Practice

Guided Practice 1

Prompt

What are two types of components in an ecosystem?

Teacher Answer Guide

Physical components like water and soil, and biological components like plants and animals.

Guided Practice 2

Prompt

How can a drought affect populations in an ecosystem?

Teacher Answer Guide

By reducing water availability, drought can decrease plant growth and food supply, leading to population declines.

Guided Practice 3

Prompt

What claim can you make about fish population decline after pollution?

Teacher Answer Guide

Pollution caused the fish population to decline, as shown by data correlating pollution timing and population decrease.

Guided Practice 4

Prompt

How do invasive predators and disease differently affect populations?

Teacher Answer Guide

Invasive predators reduce populations by eating prey, while disease reduces populations by causing illness and death.

Guided Practice 5

Prompt

Construct an argument explaining how flooding and plant loss affect populations.

Teacher Answer Guide

Flooding changes habitat conditions harming organisms; loss of plants reduces food and shelter; together these cause population declines, supported by data.

Independent Practice

  1. Foundational: What are two types of components in an ecosystem?
  2. Developing: How can a drought (a physical change) affect populations in an ecosystem?
  3. Application: Analyze a graph showing fish population decline after a factory started polluting a river. What claim can you make about the effect of pollution?
  4. Analysis: Compare two scenarios: one where an invasive predator is introduced and one where a disease affects a population. How do these biological changes differently affect populations?
  5. Challenge: Using empirical evidence from a case study, construct a written argument explaining how a physical change (like flooding) and a biological change (like loss of a plant species) together affect an ecosystem's populations.

Independent Practice Teacher Answer Key

  1. 1. Physical components (like water, soil, temperature) and biological components (like plants and animals).
  2. 2. A drought reduces water availability, which can decrease plant growth and reduce food for animals, causing populations to decline.
  3. 3. The claim is that pollution from the factory caused the fish population to decline, supported by the timing and correlation shown in the graph.
  4. 4. The invasive predator may reduce prey populations by increased predation, while disease may reduce populations by causing sickness and death. Both cause population declines but through different biological mechanisms.
  5. 5. A well-constructed argument states that flooding (physical change) alters habitat conditions, which can harm or displace organisms. The loss of a plant species (biological change) reduces food and shelter for animals. Together, these changes disrupt the ecosystem, causing population declines or shifts, supported by data showing changes in species numbers after flooding and plant loss.

Guiding Questions

  • What components make up an ecosystem?
  • How can changes to these components affect populations?
  • What evidence do you have to support your claim?
  • How does your reasoning explain the connection between evidence and claim?
  • What might happen to the ecosystem over time after a change?

Common Misconceptions

  • Students may think ecosystems are static and do not change over time.
  • Students might confuse physical and biological components or their roles.
  • Some may believe that a single change affects only one population, not the whole ecosystem.
  • Students might think evidence is just opinion rather than data or observations.
  • Students may struggle to link evidence logically to claims without clear reasoning.

Differentiation

Support and Intervention

Provide sentence starters for constructing arguments. Use graphic organizers to help link claim, evidence, and reasoning. Offer simplified data sets or visual aids for analysis.

English-Language Learner Support

Use visuals and realia to explain key vocabulary. Provide bilingual glossaries for scientific terms. Encourage peer discussion in native language before sharing in English.

Advanced and Extension

Challenge students to critique the strength of evidence in different studies. Have students design their own investigations on ecosystem changes. Encourage writing extended arguments including counterclaims and rebuttals.

Assessment

  • Observe group discussions and provide feedback on argument construction.
  • Review students' data analyses and explanations during activities.
  • Use questioning to probe understanding during exploration and explanation phases.
  • Write a brief claim and supporting evidence explaining how a change in an ecosystem affects a population.
  • List one physical and one biological component of an ecosystem and describe how each can change.
  • Write a detailed scientific argument using empirical evidence from a provided case study.
  • Create a model diagram showing how a physical or biological change affects populations in an ecosystem.

Answer Guide

  • What are two types of components in an ecosystem?
    Answer: Physical components like water and soil, and biological components like plants and animals.
  • How can a drought affect populations in an ecosystem?
    Answer: By reducing water availability, drought can decrease plant growth and food supply, leading to population declines.
  • What claim can you make about fish population decline after pollution?
    Answer: Pollution caused the fish population to decline, as shown by data correlating pollution timing and population decrease.
  • How do invasive predators and disease differently affect populations?
    Answer: Invasive predators reduce populations by eating prey, while disease reduces populations by causing illness and death.
  • Construct an argument explaining how flooding and plant loss affect populations.
    Answer: Flooding changes habitat conditions harming organisms; loss of plants reduces food and shelter; together these cause population declines, supported by data.

Real-Life Application

Encourage students to observe a nearby park or garden and note any changes in plants or animals. They can discuss with family how these changes might affect the local ecosystem populations.

Homework or Home Connection

  • Encourage students to observe a nearby park or garden and note any changes in plants or animals. They can discuss with family how these changes might affect the local ecosystem populations.

Lesson Summary

This lesson guides students to understand that ecosystems are dynamic and interconnected. Changes to physical or biological components can cause shifts in populations. By analyzing empirical evidence and constructing scientific arguments, students develop critical thinking skills and deepen their understanding of ecosystem dynamics, fulfilling NGSS standard MS-LS2-4.

Teacher Notes

Use the exact standards alignment and retrieved-source provenance stored with this enrichment.

Related Lessons