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    Home » Science Experiments for Kids » Biology » Growing Microorganisms – Dirty Potatoes

    Growing Microorganisms – Dirty Potatoes

    July 31, 2013 By Emma Vanstone

    Welcome to more Spectacular Summer Science, today we’re growing microorganisms

    Following on from our hand washing exercise last week we tried another related activity. We boiled some potatoes to destroy any microorganisms already present on the surface and then touched one of them with dirty hands leaving the other untouched.

    What would you expect to happen?

    Our hypothesis was that micro-organisms from our hands would have been transferred to the potato when we touched it, and so that one should grow more bacteria than the clean potato.

    We also added a potato left in the air and one in vinegar to see what would happen.

    What you need:

    • 2 small potatoes sliced in half
    • Boiling water – get an adult to help
    • Vinegar
    • 4 containers

    Instructions

    • Boil the potatoes for a few minutes, this is to destroy any microorganisms already present on the skin.
    • Carefully remove one potato with a spoon and place into a jar, cover the jar and label it. This is the clean potato.
    • Remove another potato but don’t cover this one, we are exposing this potato to the air.
    • Remove a third and place in a jar containing vinegar.
    • Finally remove the last potato, let it cool enough to hold and then rub it around your hands, before placing in a sealed jar.

    Potatoes

    Leave the jars on a window sill for a few days and observe and changes.

    Results

    The potato exposed  shrivelled up a little bit, and there is some evidence of micro-organism growth.

    air

    The clean potato, ended up quiet slimy, with some possible micro-organism growth.

    clean

    The dirty potato didn’t seem to have more more evidence of micro-oroganism growth than the clean potato.

    dirty

    The potato kept in vinegar looked mostly unchanged.

    DSC_0031

    Why?

    You can see that the vinegar has definitely preserved the potato. This is because vinegar is an acid and microorgansims find it hard to grow in such a hostile environment. That is why we pickle things to make them last longer.

    I was hoping to see more growth on the dirty potato, but with science things don’t always work out as you expect. It could be that my jar wasn’t airtight, or it hadn’t been boiled for long enough so there were still some bacteria on the surface.

    The healthy schools project has more information about good hygiene.

    We’d love you  join our Science Sparks community on G+ and  follow us on  Facebook, Twitter and Pinterest.

    If you take any videos of you and your children doing any of our activities please share on G+ and tag us using #ScienceSparks. I’d love to see and share them around.

    Spectacular Summer Science

    Week 1

    Day 1 –  Baking Soda Ice Cubes

    Day 2 – Slipping and Sliding

    Day 3 – Fun Heart Rate Investigation

    Day 4 – Mini Beast Hunt

    Day 5  – Pretty Flowers

    Week 2

    Day 1 – Splatter patterns

    Day 2 – Monster Tea Party

    Last Updated on October 3, 2014 by

    « Monster Tea Party
    Summer Density »

    Safety Notice

    Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

    These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

    Reader Interactions

    Comments

    1. Pinkoddy

      August 18, 2013 at 6:28 pm

      What a great experiment. Think the boys would love this but can’t see my husband liking growing germs on his window sill. May try this as an outdoor experiment. Thank you for sharing.

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