Cellular transport basics

Overview

In this lesson (Lesson 1 of 3), students are introduced to passive transport and its role in cells. They explore simple diffusion, facilitated diffusion, and osmosis using discussion, teacher visuals, and short analysis tasks that prepare them for hands-on investigations in later lessons.

Learning intentions

• Understand that passive transport moves substances without using energy from cells.
• Explain simple diffusion and why particles spread from higher to lower concentration.
• Describe facilitated diffusion as diffusion using membrane proteins.
• Explain osmosis as diffusion of water through a selectively permeable membrane.
• Use basic scientific language and models to communicate ideas.

Success criteria

• I can distinguish passive transport from active transport using clear explanations.
• I can describe simple diffusion, facilitated diffusion, and osmosis in terms of particle movement.
• I can interpret a particle diagram or model to predict the direction of net movement.
• I can justify my explanation using evidence from visuals and class discussion.

Curriculum links

• Science: Developing understanding of how living things function at the cellular level, including transport of substances across membranes.
• Science: Using scientific inquiry skills (observing, interpreting, and communicating using evidence).
• Key competencies: Thinking (making sense of models), Participating and contributing (discussions), Using language, symbols, and texts (scientific explanations and diagrams).

Lesson structure (60 minutes)

1. 0–5 min — Hook and prior knowledge

• Show two everyday examples (e.g., smell spreading in a room; food colouring in water) and ask: “What makes particles move without a fan or pump?”
• Students write a one-sentence idea about how movement happens.

2. 5–12 min — Mini-lesson: what passive transport is

• Use a simple particle model to contrast passive transport (no added energy input) with active transport (energy used).
• Emphasise “net movement from higher concentration to lower concentration” as the core rule for diffusion processes.

3. 12–24 min — Simple diffusion stations (teacher-led)

• In small groups, students view three short visual scenarios (e.g., dye particles in water, oxygen moving into cells in a diagram, glucose spread in a model).
• For each, students answer: “Where is concentration higher? Where does the net movement go? Why?”
• Teacher checks misconceptions, especially confusing “where particles start” with “where net movement ends up.”

4. 24–36 min — Facilitated diffusion: membranes and proteins

• Display an animation or particle diagram showing a membrane with “channels” or “carriers.”
• Students practise explaining: “Particles still move down a concentration gradient, but they require a protein to cross.”
• Quick class discussion: What changes compared with simple diffusion? What stays the same?

5. 36–47 min — Osmosis: water and selective permeability

• Model osmosis using a selectively permeable membrane and two solutions (e.g., water vs solute-heavy side).
• Students interpret a particle diagram and predict: “Which side gains water? What happens to cell size if used as an analogy?”
• Teacher clarifies that osmosis is specifically the diffusion of water, not all substances.

6. 47–55 min — Whole-class synthesis: “Compare and sort”

• Provide three scenario cards (simple diffusion, facilitated diffusion, osmosis) and ask students to sort them while justifying their choice in pairs.
• One or two pairs share reasoning. Class builds a comparison table on the board.

7. 55–60 min — Exit ticket

• Students complete a short response: Draw or describe the direction of net movement for each of the three processes and give one sentence explaining the reason using concentration gradient and/or selective permeability.

Resources

• Slides or printed particle-diagram visuals (diffusion, facilitated diffusion, osmosis)
• Scenario cards (teacher-made) with simple particle descriptions
• Whiteboard/table to compile a comparison summary
• Student notebooks or worksheets for station responses and exit ticket
• Coloured counters or paper cut-outs to represent particles (optional, if visuals need reinforcement)
• An index-card exit ticket template
• Timers for station transitions
• Timer and projector for short visual demonstrations

Assessment

• Formative assessment through station responses and teacher questioning (identify misconceptions about “net movement” and diffusion direction).
• Exit ticket to check whether students can correctly distinguish the three types of passive transport and justify predictions using evidence from diagrams.
• Observation of pair explanations during “compare and sort” for scientific communication and use of correct terminology.

Differentiation

• Support: Provide sentence starters (“Concentration is higher on… therefore net movement is toward…”, “Osmosis is the movement of water…”) and a partially completed comparison table.
• Support: Offer simplified diagrams with labels (higher/lower concentration, membrane, water, solute).
• Extension: Ask advanced students to explain why facilitated diffusion still does not require energy input, and to discuss limits (e.g., saturation of membrane proteins) in conceptual terms.
• EAL/SEN: Allow oral responses to be recorded by a partner; use visuals first, then consolidate vocabulary through guided modelling rather than relying on text-heavy reading.