In this activity students will compare how plastic and potato (a proxy for starch-based bioplastic) degrade in different conditions. Please note that results cannot be gathered in the same lesson.

Activity steps

1. Use the borer to remove four cylinders of potato.
2. Cut all four pieces of potato into the same length.
3. Place each potato cylinder into a separate petri dish.
4. Cut out four squares of plastic carrier bag into the same sized squares. For example 1cm by 1 cm.
5. Add a plastic carrier bag square to each of the four petri dishes already containing a potato cylinder.
6. Change the environment for each petri dish (temperature, oxygen availability, moisture). This can be done by putting one near a radiator to increase temperature, tape one closed to reduce oxygen, or placing one under compost to change several conditions at once.
7. Leave your samples for a fixed time.
8. Return to your samples and make your observations.

• Half a potato
• Plastic carrier bag
• Ruler
• Cork borer
• Knife
• Cutting tile
• Ruler
• 4 Petri dishes
• Pen to label dishes
• Balance
• Soil (optional)
• Salt water (optional)
• Oil (optional)

Fruit and veg will typically degrade in the ocean in 2 months, while some plastics will not degrade for over 600 years or more. The increase of single-use plastic means that we are producing a large amount of waste which often finds it's way into the environment where it can cause harm to the animals which live there. Currently plastic bags are not widely recycled because they can contain contaminated waste and get stuck in machinery easily. This has sparked material engineers to invent commercially available bioplastics, plastics made from natural polymer materials, which are compostable and degradable.