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Symbiosis: How Living Things Interact

Students explore the relationships that connect organisms in an ecosystem — mutualism, commensalism, parasitism, predation, and competition — and learn to classify who benefits and who is harmed.

Grade 7Ecology55 minutes1 class period5E ModelExplicit teaching4 StandardsCommon Core
Start the Lesson
Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Define symbiosis.
  • ✓Explain mutualism, commensalism, parasitism.
  • ✓Explain predation and competition.
  • ✓Classify a relationship by who benefits.
Essential Question

A bee and a flower help each other; a tick harms a dog; a lion hunts a zebra. How do scientists classify the many ways living things interact?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Relationship Explorer · Interactive

The Relationship Explorer

Project this and tap each type of interaction. Have students note who benefits, who is harmed, and an example of each.

🔗 Explore ecosystem interactions — tap eachTry it

The Lesson · 5E Model

55 minutes, five moves

Tap any phase to open the teacher moves and student actions.

1

Engage — Who Wins?

5 min

A bee + a flower, a tick + a dog — who benefits in each?

👩‍🏫 Teacher Moves

  • Show two interactions.
  • Ask who benefits/is harmed.
  • Set the goal: symbiosis.

🎒 Student Actions

  • Compare the pairs.
  • Ask who wins.
  • Predict the types.
2

Explore — Explore the Types

12 min

Students investigate.

👩‍🏫 Teacher Moves

  • Send students to the Relationship Explorer.
  • Tap each type.
  • Record who benefits/is harmed.

🎒 Student Actions

  • Tap each type.
  • Record it.
  • Note benefit/harm.
3

Explain — Classify the Relationship

13 min

Teacher explains.

👩‍🏫 Teacher Moves

  • Explain the +/+, +/0, +/− patterns.
  • Add predation and competition.
  • Show why interactions matter.

🎒 Student Actions

  • Explain the patterns.
  • Add predation/competition.
  • Explain importance.
4

Elaborate — Elaborate — Real Examples

12 min

Apply.

👩‍🏫 Teacher Moves

  • Classify real-world examples.
  • Explain the +/− for each.
  • Build a food-web interaction map.

🎒 Student Actions

  • Classify examples.
  • Explain each.
  • Map interactions.
5

Evaluate — Evaluate — Exit Ticket

5 min

Three quick checks.

👩‍🏫 Teacher Moves

  • Hand out the exit ticket.
  • Look for benefit/harm reasoning.
  • Collect as formative data.

🎒 Student Actions

  • Classify a relationship.
  • Explain who benefits.
  • Give an example.
Standards Alignment

Built to the standards you report on

Aligned to Next Generation Science Standards and Common Core literacy. State-standard crosswalks available on request.

NGSS
MS-LS2-2

Construct an explanation that predicts patterns of interactions among organisms across ecosystems.

NGSS
MS-LS2-1

Analyze data to provide evidence for the effects of resource availability on organisms.

NGSS
MS-LS2-4

Construct an argument that changes to an ecosystem affect populations.

CCSS
RST.6-8.7

Integrate visual information with text in a scientific model.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Interaction picture cards (+/− labels).
  • Sentence frame: “In ___, ___ benefits and ___ is ___.”
  • Match examples to types.

Support & Access

IEP / 504
  • Start with mutualism vs. parasitism.
  • Use clear +/− examples.
  • Classify one at a time.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Classify tricky real examples.
  • Explain how one change ripples through a web.
  • Research a symbiotic pair.
Materials

What to gather

  • 📽️Projector / board
  • 📓Science notebooks
  • 💻The Relationship Explorer
  • 🖼️Interaction cards
  • ✏️Pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

symbiosisa close relationship between speciesmutualismboth species benefitcommensalismone benefits, one unaffectedparasitismone benefits, one is harmedpredationone hunts and eats anothercompetitiona struggle for the same resourcehostthe organism a parasite lives onecosystemliving things and their environment
Evaluate

Exit Ticket

Preview the three formative checks. Tap “Sample answer” to see what mastery looks like — hide them before you print for students.

QUESTION 1
In mutualism, who benefits?
Both species benefit (a win-win, like bees and flowers).
QUESTION 2
What is the difference between commensalism and parasitism?
In commensalism one benefits and the other is unaffected; in parasitism one benefits and the other is harmed.
QUESTION 3
A lion hunting a zebra is an example of what interaction?
Predation.

Going deeper? Classify the tricky ones.

Have students research real symbiotic pairs (clownfish and anemone, remora and shark) and classify each relationship. A printable classification sheet is in the Science library.

Study · Flashcards

Study the key terms

Tap a card to flip it, then rate whether you knew it. Built from this lesson’s vocabulary.

🃏 Symbiosis & Ecosystem InteractionsFlip
Card 1
Term
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Meaning
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Practice · Quiz

Check your understanding

A quick self-check with instant feedback, drawn from this lesson’s key terms.

📝 Symbiosis & Ecosystem InteractionsQuiz
Score: 0
1 / 6
Question 1
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Practice · Worksheet

Printable worksheet

A print-and-go review sheet with a built-in answer key. Tap “Show answer key” to reveal answers, or print the clean version for students.

🖨️ Symbiosis & Ecosystem InteractionsPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: commensalism, competition, ecosystem, host, mutualism, parasitism, predation, symbiosis
  1. the organism a parasite lives on
  2. a close relationship between species
  3. living things and their environment
  4. a struggle for the same resource
  5. one benefits, one unaffected
  6. one hunts and eats another
  7. one benefits, one is harmed
  8. both species benefit

Part B · Show what you learned

  1. In mutualism, who benefits?
  2. What is the difference between commensalism and parasitism?
  3. A lion hunting a zebra is an example of what interaction?
Answer key — Part A: 1) host · 2) symbiosis · 3) ecosystem · 4) competition · 5) commensalism · 6) predation · 7) parasitism · 8) mutualism
Part B: 1) Both species benefit (a win-win, like bees and flowers). 2) In commensalism one benefits and the other is unaffected; in parasitism one benefits and the other is harmed. 3) Predation.