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SOS: Save our snacks!

 
 

Overview

Materials needed per group

  • 1 uniformly shaped snack, e.g. crisp, pretzel or biscuit
  • Address label
  • Variety of packaging materials, e.g.
    - Shredded paper
    - Card
    - Bubble wrap
    - Cotton wool
    - Brown paper
    - Tape
    - Coffee cup lids
    - Polystyrene packing peanuts
  • Scissors
  • Ruler
  • Digital scales
  • Record sheet

Practicalities

  • Begin saving packaging for this investigation about a month before – put up signs around school or send letters home to encourage people to save and donate packaging materials to you.
  • You could try and get materials for free by approaching local coffee shops and supermarkets.
  • This challenge works best with students working individually or in small teams of two or three, competing against each other.
  • When you set the challenge make sure that everyone is aware of the rules.
  • Give every team a set of packaging materials in a plastic bag. This will ensure fairness as everyone will have the same – and a hidden bonus is that it also helps contain the mess!
  • It is not necessary to be confined to an envelope, a package could be built and wrapped up.
  • This activity can last between 15 and 30 minutes if students prototype and test their designs before eventually posting them.
  • You will be posting the packages, so remember to take into account the additional time you will need to go to the post office, as well as the cost of postage (around £1–£1.50 per package is typical).
  • Allow time in a later class or session to unwrap the packages, fill in the results page and see who won the challenge.

Warning

  • Ensure the students know at the start of the challenge their aim is to keep the snack intact, otherwise there is a strong chance it will have disappeared before you even begin!

Discussion

  • What makes the strongest package?
  • What is a strong shape and how can you utilise it?
  • What is more important in building a package, the weight or how well it protects the snack?
  • How important is the cost of materials and postage in producing a package?
  • Is design important? Does a package need to look attractive?

Extensions

  • Bring in different types of packaging and discuss why and how they have been produced this way.
  • Add a control to the investigation by posting snacks in Royal Mail padded envelopes and seeing which ones come back more intact.
  • If your students need an immediate response, or your budget does not allow for postage costs, you could simply drop the packages from a great height and check them against the same survival score sheet.
  • Team up with another school (a feeder school or a foreign exchange school) and send your packages to each other and share the results.
  • Set up a 'Save Our Snacks' league in your area and get all the schools’ science clubs competing against each other.
  • Go global and join in with a similar activity in America called the Pringles Challenge.
  • Set your own additional rules, e.g. students cannot use any padding so that the activity is all about the engineering of the box, or set a size or weight limit.
  • Limit the materials available to make the activity even more challenging.
  • Give each material a ‘cost’ and allocate a budget to each team. Something very useful such as thin cardboard or bubble wrap may be a lot more ‘expensive’ than materials such as paper and plastic bags; heavy things may be cheaper than light materials. You could also allocate costs based on how recyclable materials are.
  • Create a leader board so that people can see what they are competing against – the competition could span many months.
  • Make the investigation into a theme day where students build their packages and then visit a local postal sorting office to see them put through the system.

Links to everyday life

Potato crisps

Legend has it that the potato crisp was ‘invented’ in 1853 in the United States by a Native American chef called George Crum. The railway magnate Cornelius Vanderbilt was eating at the restaurant where Crum worked. Vanderbilt, a notoriously fastidious customer, repeatedly sent his potato chips back to the kitchen, complaining that they were cut too thickly. The exasperated Crum eventually cut the potato into wafer-thin slices, frying them in oil until they were crispy. Vanderbilt enjoyed them, and the crisp was born.

Crisps did not appear in Britain until the 1910s, and were not manufactured on any scale until Frank Smith started to make them in a London garage in 1920. Today they are Britain’s most popular snack.

Shaped potato crisps, 1990.
Shaped potato crisps, 1998.

Post and Packaging

The message on this poster from the 1940s is as important to this activity as it was then!

'Smaller parcels, please' BR Poster 1946-1965 
British Rail Poster, 1946-1965.

Trains have been used to deliver mail since the rise of the railways in the early 1800s. For many years letters and packages were sorted aboard ‘travelling post offices’ before being dropped off at stations to be delivered.

Sorting mail on the TPO, Newcastle to St Pancras, 1987.
Sorting mail on the travelling post office between Newcastle and London St Pancras, 1987.

Fragile objects, such as this clay piping, have to be packaged carefully before being transported. Here the pipes are being wrapped tightly in straw, then packed tightly together in the delivery van to minimise breakages.

Delivery van, 1933.
Delivery van, 1933.

The science

Throughout the activity students have to make choices based on their prior experience of the various materials on offer and by testing prototypes made with them. There is a balance to be struck between producing the most protective package and making it as small and light as possible. If students go to either extreme they will lose the challenge, so each group will have to decide how far to focus on each consideration.

The snacks are brittle and cannot flex without breaking, so the challenge is to produce a structure that will absorb or redirect any external forces that are applied in transit. Clever design will allow light materials to become strong so that they can spread the stress from a crushing force along their whole structure and away from the snack. Materials that absorb and spread the energy from a sharp impact, e.g. cotton wool, polystyrene and shredded paper, will help to cushion the snack.