Breeding bacteria

Does your child need an incentive to wash their hands? Growing greeblies might be the motivation you’ve been looking for!

What you’ll need:

– Petrie dish of agar

– Cotton buds


1. Buy some sterile petrie dishes with agar in the them and a set of sterile swabs.

2. Using a cotton bud, swab a certain area of your house (i.e. collect a sample by rubbing the cotton bud on a surface of your choice).

3. Rub the swab over the agar with a few gentle strokes before putting the lid back on and sealing the petrie dish.

4. Allow the dish to sit in a warm area for 2 to 3 days.

5. Check the growth of the bacteria each day.

6. Try repeating the process with a new petrie dish and swab from under your finger nails or between your toes.

7. Dispose of the bacteria by wrapping up the petrie dish in old newspaper and placing in the rubbish (don’t open the lid).

What’s happening?

The agar plate provides the perfect warm conditions for bacteria to grow. The microorganisms on the plate will grow into individual colonies, each a clone (exact copy) of the original. The bacteria you get will grow pretty quickly and you will be able to see it with the naked eye in quite a short time. Different samples will produce different results, which is why it’s interesting to take a swab sample from your own body as well as from around the house.

Bacteria is everywhere. It grows in soil, water, on plants and on humans too. Thankfully, our immune system usually does a great job of protecting us from bacteria.

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