The Life Starter
Sign up
All courses/Life

Course 236 · Life course 58

Explain Food Webs and Ecosystem Change

A food-web and carbon-cycle model explaining a fictional ecosystem disturbance, with a supported prediction and an alternative explanation. Six introductory lessons use supplied practice cases.

Before you start

Use paper or a free text document; every core input is supplied in the lessons.

Explain How Cells Support Living Things See everything you’ll need

Free download · Original practice data · No external account required. Download the starter pack

What you’ll leave with

A food-web and carbon-cycle model explaining a fictional ecosystem disturbance, with a supported prediction and an alternative explanation.

Start course Start without an account. Sign in to save lesson progress across devices.

Your project

Start with the practice files. Build your project one lesson at a time.

Practice files are free without an account. Sign in to save your project record in My Proof: a description, checklist, and optional work link. Keep the original files in your own app or notebook; saving a project record does not upload them.

  1. Get your materialsDownload practice filesSupplied practice cases, a blank working record, complete lesson instructions, and annotated worked examples.
  2. Make your projectView the project checklist Work in your own notebook, document, or software. Use the supplied practice examples when you prefer.
  3. Keep a private recordSave a project record Sign in to save a description and checklist, then return to update them.
Course handbook

Know the route before you begin.

Here’s what you’ll need and what you’ll make. You can return to this guide during any lesson.

Who this is for

Learners aged 14+ building subject foundations and practical independence. Adults can use the same supplied cases.

Prepare before lesson one
  • Use paper or a free text document; every core input is supplied in the lessons.
  • A basic calculator is optional; show the method, units and checks.
  • Suggested earlier course: Explain How Cells Support Living Things
Your final project

Finish with proof you can use.

A food-web and carbon-cycle model explaining a fictional ecosystem disturbance, with a supported prediction and an alternative explanation.

Save a project record in My Proof
See project checklist and review criteria

Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.

What to include

  • Classify organism roles and nonliving conditions.
  • Draw all supplied food-to-eater and decomposer links.
  • Separate carbon cycling from energy flow and calculate the supplied fraction.
  • Classify interactions from both partners’ stated effects.
  • Trace a disturbance with an alternative food path.
  • Write a bounded explanation of the supplied counts and complete changed cases.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Method: applies the course-specific rules to the supplied cases with visible intermediate work.
  • Accuracy: results agree with the stated facts, units, boundaries and independent checks.
  • Reasoning: explains why the result follows and identifies a limitation or unresolved question.
  • Transfer: completes changed cases and revises the final project when a relevant assumption changes.
Three ideas to help you along the way
Three useful ideas

The rules behind the steps.

01

Use the supplied mechanism

Producers use light or chemical energy to build organic material; consumers obtain food from other organisms; decomposers break down dead material and return matter to other parts of the ecosystem. These roles describe supplied feeding processes, not whether an organism is good or bad. An ecosystem also includes nonliving conditions.

02

Connect the middle steps

Energy enters many ecosystems as sunlight, moves through organisms and becomes dispersed heat; a continuing energy input is needed. Carbon matter can move among air, producers, consumers, dead material and soil. Photosynthesis incorporates carbon from carbon dioxide; respiration and decomposition can return carbon dioxide. Energy flow and matter cycling are related but distinct.

03

Explain the final boundary

An explanation connects an observation to a mechanism and acknowledges plausible alternatives. A food-web prediction is not a proof of causation from one before/after comparison. Integrate energy, carbon and interaction models while keeping observed data separate from predicted effects.

What do these words mean?
Key words

Key terms worth knowing.

Producer
Organism using light or chemical energy to build organic material.
Consumer
Organism obtaining food from other organisms.
Decomposer
Organism breaking down dead organic material.
Food web
Connected feeding relationships represented with transfer directions.
Abiotic
Nonliving environmental component.
Mutualism
Interaction with stated benefits to both participating species.
Your route

6 lessons.
One useful project.

Work in order the first time. Each lesson makes something the next lesson can use.

  1. 1
    Up next

    Identify roles in an ecosystem

    Classify feeding roles and abiotic influences from supplied organism processes.

  2. 2
    13 min

    Draw a web with transfer arrows

    Translate supplied feeding statements into directional arrows and trace multiple paths.

  3. 3
    11 min

    Separate energy flow from carbon cycling

    Distinguish energy flow from carbon cycling and calculate a supplied transfer fraction.

  4. 4
    10 min

    Classify organism interactions

    Classify ecological interactions from resource use and supplied effects on both partners.

  5. 5
    12 min

    Predict connected effects of a disturbance

    Trace direct and indirect disturbance paths and state conditions for a prediction.

  6. 6
    15 min

    Write a bounded ecosystem explanation

    Integrate a web and carbon model into an evidence-based explanation with an alternative.

Use the tools

Tools to help you practice.

See all tools
ZIP · practice files

Explain Food Webs and Ecosystem Change practice files

Supplied practice cases, a blank working record, complete lesson instructions, and annotated worked examples.

Text worksheet

Your course project worksheet

A downloadable text worksheet with each lesson’s working output, space for your answers, and the shared final-project checklist. Save your own copy.

Source transparency

Sources and further study.

Explore the references behind the lessons and take your learning further. Source notes explain access and reuse.

OpenStax: ecosystem energy and food webs
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

OpenStax: biogeochemical cycling
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

OpenStax: community interactions
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

Ready when you are

Start with the first useful move.

You’ll always know what to do, what to make, and where to go next.

Start lesson one