Polymer Foundations

Overview

Lesson 13 of 20 builds the class understanding of organic “layers” by introducing polymers: what they are and why addition polymers are significant in real materials. Students will connect particle-level structures to material properties and practise planning the investigation thinking style needed for later practical work.

Learning intentions

• WALT define polymers and describe them as large molecules made from repeating units.
• WALT explain how addition polymerisation forms addition polymers from monomers.
• WALT link polymer structure (repeating units and bonding) to material significance (properties and uses).
• WALT communicate scientific understanding clearly using correct vocabulary.

Success criteria

• I can correctly define a polymer and distinguish it from a small molecule.
• I can describe addition polymerisation as monomers joining to form a polymer chain (without needing a full mechanism).
• I can explain at least two ways polymer properties affect their significance in everyday materials.
• I can use accurate scientific language and a simple model to explain my reasoning.

Curriculum links

• Science learning focus: Building understanding of particles and properties of matter through models (linked to NZC Science “Nature of Science” and “Physical world” strands).
• Key competencies: Thinking (link evidence to explanations), Participating and contributing (group discussion), Communicating (models, diagrams, scientific language).
• Assessment alignment: This lesson supports later practical investigation skills by focusing on method thinking, data-free model reasoning, and clear reporting consistent with NCEA internal investigation expectations (AS91187 “Carry out a practical Earth and Space Science investigation” structure as a general template for purpose–method–data–conclusion–science links, though the science here is chemistry/organic materials).

Lesson structure (60 minutes)

1. 0–5 min · Hook and recall. Teacher shows three everyday items (e.g., takeaway container, stretchy bag, nylon fabric swatch) and asks, “What do they have in common as materials?” Students do a quick write: one possible shared explanation using “small particles” or “molecules”.

2. 5–15 min · Mini-lesson: polymer definition. Teacher introduces polymers as large molecules made from repeating units and contrasts polymers with small molecules; students annotate a class “polymer vs small molecule” comparison chart.

3. 15–25 min · Modelling addition polymers. Teacher demonstrates a simple chain-building model using monomer cards (e.g., M–M–M) to show how addition polymerisation forms an addition polymer chain. Students sequence cards into a polymer chain, then complete a labelled diagram: monomer → repeating unit → polymer chain.

4. 25–35 min · Property-significance link. Teacher gives a short set of prompt statements (e.g., “Long chains can tangle,” “Some polymers are flexible,” “Some are strong,” “Some are resistant to water”). Students work in pairs to match statements to plausible properties and write one “because” explanation using polymer-chain ideas.

5. 35–48 min · Group task: Polymer significance gallery. Teacher assigns each group a polymer context card (e.g., packaging films, fibres/clothing, household plastics). Students create a 1-page “significance poster” with:

• polymer name (or generic class)
• monomers/idea of repeating units (simplified)
• two properties likely to matter
• one use and a “structure → property → use” reasoning link Teacher circulates to check accuracy of polymer and addition-polymer language.

6. 48–55 min · Whole-class share and misconception check. Teacher facilitates a brief gallery walk discussion: groups share one key chain/property/use link; teacher highlights common errors (e.g., thinking polymers are just “big” without repeating units, or confusing addition with unrelated processes). Students revise one sentence in their poster using teacher feedback.

7. 55–60 min · Exit ticket. Students answer: (1) “Define a polymer in 1–2 sentences,” (2) “In addition polymerisation, what happens to monomers?” (3) “Give one reason polymer properties make them significant.”

Resources

• Polymer vs small molecule comparison chart (print or slide)
• Monomer and repeating-unit/chain cards (paper or magnetic)
• Polymer chain diagram templates (A4 sheets)
• Polymer context cards (3–5 different cards for group work)
• Sticky notes or markers for gallery walk
• Short “because” sentence starters (e.g., “Because the polymer has repeating units…”, “Long chains can… so the material…”)
• Polymer sample images or physical swatches (if available)

Assessment

• Formative checks: teacher listens during partner “because” explanations for correct use of repeating units and chain ideas.
• Formative checks: teacher reviews the group posters mid-lesson for inclusion of structure → property → use reasoning.
• Exit ticket: definition accuracy, addition-polymer statement, and one property–significance link.

Differentiation

• Support: provide sentence starters for explanations; offer a scaffold diagram showing monomer, repeating unit, and polymer chain; pre-teach key vocabulary (polymer, monomer, repeating unit, addition polymer).
• Support: allow students to use simplified models (card sequences) rather than expecting detailed mechanisms.
• Extension: challenge students to justify which property is most important for a given use (e.g., flexibility vs strength) and to improve scientific wording using “repeating units” and “chain length/tangling” ideas.
• EAL/SEN: supply a word bank and sentence frames; allow oral responses first, then students write a final polished exit ticket response.