Lesson plan: The lunchbox investigation (ages 8–11)

Lesson overview

• Title: The lunchbox investigation — where does our plastic come from, and where does it go?
• Age band: 8–11 (England Years 3–6; US Grades 3–5; Australia Years 3–6)
• Duration: 45 minutes (extend to 60 with the persuasive-writing task)
• Subject: Science, with Geography and English links
• Made by: No Plastic Today. Funded by: No Plastic Today (no sponsors, no industry funding). Licence: CC BY 4.0.

Learning objectives

• I can count and group the plastic in a typical lunchbox and turn the count into a class total.
• I can explain, using a real number with a source, why so little plastic is recycled.
• I can describe one way plastic changes an environment and one danger this poses to living things.
• I can choose a swap and explain why it is a good one (cost, ease, how much plastic it avoids).

Curriculum codes

• England National Curriculum Science Year 4 "Living things and their habitats": recognise that environments can change and that this can sometimes pose dangers to living things. Year 5 "Properties and changes of materials": compare and group together everyday materials on the basis of their properties; give reasons, based on evidence, for the particular uses of everyday materials.
• England National Curriculum Geography KS2 "Human and physical geography": the distribution of natural resources. English KS2: writing to persuade (extension task).
• Next Generation Science Standards (NGSS): 5-ESS3-1 (obtain and combine information about ways individual communities use science ideas to protect the Earth's resources and environment); 3-5-ETS1-1 (define a simple design problem reflecting a need); 3-5-ETS1-2 (generate and compare multiple possible solutions).
• Australian Curriculum v9: Science Year 4 Chemical sciences AC9S4U03 (natural and made materials and their properties) (verify); Year 6 Chemical sciences AC9S6U04 (reversible and irreversible changes) (verify, optional link); humanities and social sciences (HASS) Year 4 Geography (sustainable use and management of resources and waste) (verify); Design and Technologies Years 3–6; Sustainability cross-curriculum priority.
• International Baccalaureate (IB) Primary Years Programme (PYP): "Sharing the planet"; suitable as a PYP exhibition starting point.

Materials

• Six "typical lunchbox" photo cards, or (better) six real lunchboxes brought from home with permission, contents unnamed.
• Tally sheet per group (columns: bottle; drink carton and straw; crisp packet; cling film; sandwich bag; yoghurt or fruit pot; cutlery; wrapper; other).
• Weight card (one per group) with these approximate weights: drink bottle 10 g; straw 0.4 g; crisp packet 5.4 g; plastic cutlery 2.6 g per piece; yoghurt pot about 5 g; cling film about 2 g per sandwich; sandwich bag about 2 g. Sources: European Commission single-use plastics study, 2018, Table A2.1 (ec.europa.eu/environment/pdf/waste/Study_sups.pdf) and industry bottle data summarised at bottlefirst.com/what-does-a-water-bottle-weigh/
• Three "habitat" cards: river, beach, open ocean, each with the fact printed on the back (see Main activity, Part 3).
• Whiteboard for the class total; calculators optional.
• The "Where does my plastic go?" explainer for ages 8–11 (on this site) for the starter.

Starter (7 minutes)

• Show one empty drinks bottle. Ask: "This bottle has three possible journeys after I finish it. What are they?" Take answers, then reveal: bin to landfill; dropped on the ground to a river to the sea; recycling bin to a new product.
• Reveal the number: "Around the world, only about 9% of plastic waste was recycled in 2019 (Organisation for Economic Co-operation and Development (OECD) Global Plastics Outlook: oecd.org/en/about/news/press-releases/2022/06/global-plastic-waste-set-to-almost-triple-by-2060.html)." Ask: "If only 9 in 100 get the good ending, what is the smartest thing to do with the other 91?" Steer towards "don't make them in the first place".

Main activity (28 minutes)

• Part 1, tally (8 minutes): in groups of four, count every single-use plastic item in your lunchbox or lunchbox card. Record on the tally sheet. Combine the group totals on the board: "items per day for our class".
• Part 2, weigh it up (8 minutes): using the weight card, groups convert their count into grams. Then multiply: grams per day x 5 days x 38 school weeks = grams per year for the class. Convert to kilograms. Ask: "How many 10 g bottles is that?" (Divide by 10.) Groups write the class figure on a sticky note and put it on the board.
• Part 3, habitat cards (7 minutes): each group reads one habitat card and reports the fact to the class.
• River card: "More than 1,000 rivers carry 80% of the plastic that flows from rivers into the sea. Most are small rivers running through towns and cities, not just a few giant ones (Meijer and others, Science Advances, 2021: doi.org/10.1126/sciadv.aaz5803)." Question: "Does our town have a river or stream? Where would a dropped wrapper end up?"
• Beach card: "In one big scientific count, 914 different kinds of sea animal had been found tangled in plastic or with plastic inside them (Kühn and van Franeker, Marine Pollution Bulletin, 2020: doi.org/10.1016/j.marpolbul.2019.110858)." Question: "Why might a turtle mistake a plastic bag for food?"
• Ocean card: "The 'Great Pacific Garbage Patch' is not an island you could stand on. It is a huge area, about 1.6 million square kilometres, of mostly tiny floating pieces, and nearly half the weight is lost fishing nets (Lebreton and others, Scientific Reports, 2018: doi.org/10.1038/s41598-018-22939-w)." Question: "Why is tiny plastic harder to clean up than big plastic?"
• Part 4, choose a swap (5 minutes): groups pick the one item from their tally that (a) they had the most of and (b) has an easy swap. Complete the sentence frame: "We would swap ___ for ___ because it saves about ___ grams a year and it is ___ (cheaper / easy / already at home)."

Plenary (10 minutes)

• Each group presents its swap in one sentence. Class votes for the top three; these become the class's "three swaps" for the term.
• Ask the reflection question: "We said environments can change and that can be dangerous for living things. Which of our swaps helps a river, a beach or the ocean, and how?"
• Optional: enter the class figure and the three swaps into the Classroom Plastic Audit tool (on this site) so you can compare next term.

Assessment

• Tally sheet and calculation: accurate counting, correct multiplication, sensible units (g to kg).
• Habitat card report: can the pupil state the fact and answer the question with a reason?
• Swap sentence: does it include a number and a reason? (NGSS 3-5-ETS1-2: comparing solutions.)

Differentiation

• Support: give a pre-filled tally with the totals and let the group do only the grams step; provide a multiplication grid; use the picture version of the tally.
• Challenge: ask pupils to work out the whole-school figure (multiply by number of classes) and to write it as a comparison ("that is the same weight as ___"); ask them to rank all nine items by grams per year and explain why the heaviest item is not always the best swap.
• English as an additional language (EAL): pre-teach tally, total, swap, habitat; pair with a fluent reader for the habitat cards.

Extension (English, 15 minutes)

• Write a persuasive paragraph to the person who packs your lunch, using the class number, one habitat fact with its source, and one polite request. Pupils can use the "Convince your parents" cards (on this site) for sentence starters.

Safety and sensitivity

• Never single out a child's lunchbox. Use photo cards or anonymous boxes. Say clearly that families choose what they can afford and what is available; the goal is to find easy swaps, not to judge.