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Energy Flow: Why Ecosystems Are Pyramids

Students discover why food chains form a pyramid — only about 10% of energy passes from one level to the next, so there’s far less energy at the top, which is why top predators are always rare.

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

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Trace energy flow up a food chain.
  • ✓Explain the 10% rule.
  • ✓Name the trophic levels.
  • ✓Explain why top predators are rare.
Essential Question

Why are there thousands of grass plants, hundreds of rabbits, but only a few foxes in one field? What happens to all the energy?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Energy Pyramid · Interactive

The Energy Pyramid

Project this and change the producer energy. Watch how only ~10% passes to each higher level — which is why the pyramid narrows toward the top.

🔺 Change the base energy — watch it shrink upwardTry it
Producer energy: 10000 kcal

The Lesson · 5E Model

55 minutes, five moves

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

1

Engage — Where’s the Energy?

5 min

Lots of grass, some rabbits, few foxes — why?

👩‍🏫 Teacher Moves

  • Show a food chain’s numbers.
  • Ask why the top is small.
  • Set the goal: energy flow.

🎒 Student Actions

  • Study the numbers.
  • Wonder about the top.
  • Predict the reason.
2

Explore — Explore the Pyramid

12 min

Students investigate.

👩‍🏫 Teacher Moves

  • Send students to the Energy Pyramid.
  • Change the base energy.
  • Note the 10% drop.

🎒 Student Actions

  • Change the base.
  • Read each level.
  • Note the drop.
3

Explain — The 10% Rule

13 min

Teacher explains.

👩‍🏫 Teacher Moves

  • Explain energy lost as heat.
  • Only ~10% passes up.
  • Name the trophic levels.

🎒 Student Actions

  • Explain the loss.
  • Explain 10%.
  • Name the levels.
4

Elaborate — Elaborate — Pyramid Math

12 min

Apply.

👩‍🏫 Teacher Moves

  • Calculate energy at each level.
  • Explain why top predators are rare.
  • Connect to real food chains.

🎒 Student Actions

  • Do the math.
  • Explain rare predators.
  • Use a real chain.
5

Evaluate — Evaluate — Exit Ticket

5 min

Three quick checks.

👩‍🏫 Teacher Moves

  • Hand out the exit ticket.
  • Look for the 10% idea.
  • Collect as formative data.

🎒 Student Actions

  • Explain 10%.
  • Name a level.
  • Explain the shape.
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-LS2-3

Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.

NGSS
MS-LS2-4

Construct an argument that changes to an ecosystem affect populations.

NGSS
MS-LS2-1

Analyze data for the effects of resource availability on organisms.

CCSS
RST.6-8.7

Integrate quantitative information with text in a model.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Trophic-level picture cards.
  • Sentence frame: “Only ___% of energy passes up.”
  • Stack a pyramid of cups.

Support & Access

IEP / 504
  • Focus on “less energy at the top.”
  • Use round numbers.
  • Provide a labeled pyramid.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Calculate energy through four levels.
  • Explain biomass pyramids.
  • Predict the effect of removing a level.
Materials

What to gather

  • 📽️Projector / board
  • 📓Science notebooks
  • 💻The Energy Pyramid
  • 🧮Calculators
  • ✏️Pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

energy pyramida diagram of energy at each leveltrophic levela feeding level in a food chainproduceran organism that makes its own foodconsumeran organism that eats others10% ruleonly ~10% of energy passes upbiomassthe total mass of living thingsfood chaina path of energy through organismsheatenergy lost at each level
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
About how much energy passes from one level of the pyramid to the next?
About 10%.
QUESTION 2
Why are there fewer top predators than producers?
Because so little energy (only ~10% each level) reaches the top — there isn’t enough to support many top predators.
QUESTION 3
What happens to the other ~90% of the energy at each level?
It is lost as heat and used up by the organisms’ life processes.

Going deeper? Do the pyramid math.

Have students start with a producer energy value and calculate the energy at each higher level using the 10% rule. A printable energy-pyramid worksheet 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.

🃏 Energy Flow & the Energy PyramidFlip
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.

📝 Energy Flow & the Energy PyramidQuiz
Score: 0
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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.

🖨️ Energy Flow & the Energy PyramidPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: 10% rule, biomass, consumer, energy pyramid, food chain, heat, producer, trophic level
  1. the total mass of living things
  2. an organism that eats others
  3. an organism that makes its own food
  4. a diagram of energy at each level
  5. only ~10% of energy passes up
  6. a feeding level in a food chain
  7. a path of energy through organisms
  8. energy lost at each level

Part B · Show what you learned

  1. About how much energy passes from one level of the pyramid to the next?
  2. Why are there fewer top predators than producers?
  3. What happens to the other ~90% of the energy at each level?
Answer key — Part A: 1) biomass · 2) consumer · 3) producer · 4) energy pyramid · 5) 10% rule · 6) trophic level · 7) food chain · 8) heat
Part B: 1) About 10%. 2) Because so little energy (only ~10% each level) reaches the top — there isn’t enough to support many top predators. 3) It is lost as heat and used up by the organisms’ life processes.