Plastics Recycling

Overview

Lesson 17 of 20 in “Exploring Organic Chemistry Layers” builds on students’ prior understanding of polymers and chemical structure by investigating real-world recycling of plastics, the environmental impacts of plastic waste, and best-practice disposal/management. Students work through a short, practical investigation and use evidence to justify decisions, aligned to carrying out practical science investigations.

Learning intentions

Students will be able to:

• plan and carry out a practical Earth and Space Science investigation using a scientific method and measurable variables (where applicable to plastics waste in the environment)
• record and process raw data to compare recycling outcomes or rates
• interpret findings to draw conclusions linked to a science-based claim
• explain the Earth and Space Science connections by relating plastic waste to environmental impacts

Success criteria

• I can state a clear purpose for my investigation and link it to a scientific context.
• I can describe my method, including ranges for key variables, how I measure them, and how I keep other variables controlled.
• I can process my raw data (eg averages/percentages) to make a conclusion that matches the purpose.
• I can explain how the results connect to environmental impacts of plastics in Earth systems.

Curriculum links

• AS91187 — Carry out a practical Earth and Space Science investigation (purpose, method with key-variable ranges and measurement, raw data, processing, interpretation, Earth and Space Science links, reporting)
• Scientific literacy and investigation practices: collecting, processing and interpreting evidence to support conclusions
• Key competencies: using language/symbols to record data and explain reasoning; managing self to follow method steps; relating to others through group roles; thinking critically about evidence and uncertainty

Lesson structure (60 minutes)

1. 0–5 min · Starter scenario. Teacher displays 3 short prompts: “Does recycling reduce landfill?” “What happens to plastics that are not recycled?” “Why do some plastics get recycled more than others?” Students choose one prompt and write a 2-sentence hypothesis or claim they can test with evidence.

2. 5–12 min · Mini-teach: from polymer to waste pathway. Teacher revises key ideas: plastic types, contamination, collection streams, and what “recycling” really means (reprocessing vs downcycling vs energy recovery). Students complete a quick “Claim–Evidence–Reasoning” scaffold using one idea from the starter (no internet needed).

3. 12–20 min · Introduce the practical investigation. Teacher sets the class investigation question: “How does contamination level affect the ‘recyclability’ outcome in a simplified sorting/acceptance test?” Students form groups of 3–4 and review the method sheet; teacher emphasises measurable variables, consistent handling, and safe procedures.

4. 20–35 min · Practical data collection. Teacher demonstrates how to run the simplified test:

• Students use labelled sample cups (clean, lightly soiled, heavily soiled) of common plastic items (eg bottles/caps/containers) and record whether each item would be accepted by a typical recycling process in a “screening” checklist (outlined on the method sheet). Students count and record outcomes for each contamination category and ensure raw data is captured in a table (counts per category, acceptance decisions, notes on reasons).

5. 35–42 min · Processing data. Teacher models one processing step: acceptance rate (%) = accepted ÷ total × 100, then asks students to compute for their group. Students calculate acceptance rates, mean/median if needed (depending on design), and construct a simple bar chart or percentage table.

6. 42–50 min · Interpretation and conclusion. Teacher prompts: “What does the pattern suggest? What evidence supports your conclusion? What could be improved to increase reliability?” Students write a 1-paragraph conclusion tied to purpose: what changed, how you know, and one limitation (eg small sample size or simplified acceptance checklist).

7. 50–57 min · Earth and Space Science connection. Teacher guides discussion: plastics waste affects land, waterways and oceans; microplastics and chemical additives can move through Earth systems. Students add two sentences linking results to environmental impacts (eg contamination can reduce recycling and increase pollution pathways).

8. 57–60 min · Exit ticket. Students submit:

• one evidence-based statement (“Our data show…”)
• one improvement to method reliability/validity (“Next time we would…”)

Resources

• Investigation method sheet (purpose, variables, ranges, measurement instructions, checklist criteria)
• Sample materials: labelled “clean/lightly soiled/heavily soiled” plastic items
• Data tables and graph paper (or offline spreadsheet template)
• Timer for consistent processing intervals
• Safety glasses and gloves (if handling soiled items)
• Markers, rulers, poster paper
• Station labels for controlling group roles (recorder, measurer, quality-checker, presenter)

Assessment

• Formative checks during the practical: teacher observes whether groups record raw data immediately and follow the method consistently.
• Formative check at processing time: teacher reviews acceptance-rate calculations and bar chart/percentage table for accuracy.
• Exit ticket assesses alignment with AS91187 elements: purpose-to-conclusion link and one method improvement for reliability.

Differentiation

• Support: provide sentence starters for purpose, method description, and conclusion (eg “The purpose of this investigation was to…” “We measured…” “Our key variable was…”).
• Support: give a partially completed data table and a checklist example for acceptance decisions.
• Extension: groups justify their checklist criteria using science ideas (eg why contamination reduces recycling efficiency) and suggest additional controls (eg repeat trials, larger sample set, consistent sample sizes).
• EAL/SEN: allow oral rehearsal of conclusion with the group; provide visual variable labels (colour-coded) to reduce reading load.