Home›Lesson Plans›Science›Cell Biology · Grade 9

Cell Transport: Moving Across the Membrane

Ninth graders learn how substances move in and out of cells — passive transport (diffusion and osmosis, no energy) and active transport (against the gradient, using energy) — and how tonicity affects a cell.

Grade 9Cells55 minutes1 class period5E ModelExplicit teaching4 StandardsNGSS
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Lesson at a Glance

Everything you need before the bell rings

Learning Objectives

Students will be able to…

  • ✓Explain passive transport.
  • ✓Explain diffusion and osmosis.
  • ✓Explain active transport.
  • ✓Predict effects of tonicity.
Essential Question

A cell’s membrane is a gatekeeper — letting some things in, pushing others out. How do molecules cross it, and why does the surrounding solution make a cell swell or shrink?

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Lesson Phases
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Vocabulary Terms
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Standards Aligned
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Interactive Task
Explore · Interactive

The Cell Transport Explorer

Project this and tap each type of transport. Have students learn how molecules cross the membrane — with and without energy!

🧫 Explore cell transport — tap eachTry it

The Lesson · 5E Instructional Model (Engage · Explore · Explain · Elaborate · Evaluate)

55 minutes, five moves

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

1

Engage — The Gatekeeper

5 min

The cell membrane lets some things in and keeps others out — how?

👩‍🏫 Teacher Moves

  • Show a cell membrane.
  • Ask how things cross it.
  • Pose the question.

🎒 Student Actions

  • See the membrane.
  • Wonder how.
  • Predict the idea.
2

Explore — Explore Transport

12 min

Students investigate.

👩‍🏫 Teacher Moves

  • Send students to the Cell Transport Explorer.
  • Record each type.
  • Note energy use.

🎒 Student Actions

  • Tap each type.
  • Record it.
  • Note energy.
3

Explain — Passive & Active

13 min

Students explain.

👩‍🏫 Teacher Moves

  • Explain diffusion and osmosis.
  • Explain active transport.
  • Explain tonicity.

🎒 Student Actions

  • Explain passive.
  • Explain active.
  • Explain tonicity.
4

Elaborate — Predict Effects

15 min

Students elaborate.

👩‍🏫 Teacher Moves

  • Predict a cell in salt water.
  • Predict a cell in pure water.
  • Explain the water movement.

🎒 Student Actions

  • Predict shrink.
  • Predict swell.
  • Explain it.
5

Evaluate — Evaluate

5 min

Students conclude.

👩‍🏫 Teacher Moves

  • Compare passive and active.
  • Predict a tonicity effect.
  • Hand out the exit ticket.

🎒 Student Actions

  • Compare them.
  • Predict it.
  • Complete the exit ticket.
Standards Alignment

Built to the standards you report on

Aligned to the Next Generation Science Standards (High School Life Science).

NGSS
HS-LS1-2

Develop a model illustrating how cell structures provide functions.

NGSS
HS-LS1-3

Plan an investigation of how feedback maintains homeostasis.

NGSS
HS-LS1-1

Explain the role of cellular structures.

NGSS
SEP-2

Developing and using models.

Differentiation

One lesson, every learner

Multilingual Learners

ELL / EMERGING READERS
  • Concentration-gradient diagram.
  • Sentence frame: “Water moves from ___ to ___.”
  • Model with a demo.

Support & Access

IEP / 504
  • Start with diffusion.
  • Use a food-coloring demo.
  • Focus on high-to-low.

Stretch & Extend

GIFTED / EARLY FINISHERS
  • Model osmosis in a potato.
  • Explain facilitated diffusion.
  • Solve a tonicity problem.
Materials

What to gather

  • 📽️Projector / board
  • 🧫Membrane models
  • 💻The Cell Transport Explorer
  • 🧪Osmosis demo
  • ✏️Pencils
  • 🎫Exit-ticket slips
Vocabulary

Key terms — hover for a quick definition

cell membranethe barrier around a cellpassive transportmovement with no energydiffusionspreading from high to low concentrationosmosisdiffusion of wateractive transportmovement using energyconcentration gradienta difference in concentrationhypertonichigher solute outside; cell shrinkshypotoniclower solute outside; cell swells
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
What is the difference between passive and active transport?
Passive transport needs no energy (high to low concentration); active transport uses energy to move molecules low to high.
QUESTION 2
What is osmosis?
The diffusion of water across a membrane.
QUESTION 3
A cell placed in salt water (hypertonic) will do what?
Shrink — water leaves the cell.

Elaborate: the potato lab.

Have students place potato slices in salt water and pure water, then measure the mass change to see osmosis in action. A printable cell-transport 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.

🃏 Cell TransportFlip
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.

📝 Cell TransportQuiz
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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.

🖨️ Cell TransportPrint
Name: ________________________
Date: ____________

Part A · Write the word that matches each meaning

Word bank: active transport, cell membrane, concentration gradient, diffusion, hypertonic, hypotonic, osmosis, passive transport
  1. a difference in concentration
  2. lower solute outside; cell swells
  3. spreading from high to low concentration
  4. the barrier around a cell
  5. movement using energy
  6. diffusion of water
  7. movement with no energy
  8. higher solute outside; cell shrinks

Part B · Show what you learned

  1. What is the difference between passive and active transport?
  2. What is osmosis?
  3. A cell placed in salt water (hypertonic) will do what?
Answer key — Part A: 1) concentration gradient · 2) hypotonic · 3) diffusion · 4) cell membrane · 5) active transport · 6) osmosis · 7) passive transport · 8) hypertonic
Part B: 1) Passive transport needs no energy (high to low concentration); active transport uses energy to move molecules low to high. 2) The diffusion of water across a membrane. 3) Shrink — water leaves the cell.