Teaching overview

Learning points

  • Bacteria are the smallest living organisms in the world – made up of just one cell.
  • Humans need good bacteria to digest food and fight illness.
  • A single human mouth can contain up to 100 billion bacteria.

Curriculum keywords

  • STEM
  • Health
  • Body Systems

5 things you didn't know

What are bacteria?

1. Bacteria are tiny organisms made up of just a single cell. They can be as small as half a micrometre – for comparison, a human hair is roughly 75 micrometres wide!

Good bacteria

2. A lot of people think bacteria are always bad, but we actually need bacteria to digest food, fight disease and prevent allergies developing. Yoghurt is a great source of friendly bacteria!

Bacteria in your mouth

3. People can have up to 100 billion bacteria in their mouth – that’s 13 times the number of humans on Earth.

Bacteria make you fart

4. Your stomach bacteria have to work overtime to digest any beans you eat, which means they produce lots of waste gas – this is why beans make you fart!

Glow-in-the-dark bacteria

5. Conditions in the American Civil War meant that some soldiers’ wounds became infected with bacteria… that glowed in the dark!

Spark a discussion

  • How many cells make up a single bacterium?
  • Why do humans need bacteria?
  • Does your mouth have any bacteria in it?

Explore our resources

Complete your lesson with teaching resources on microorganisms from Tigtag.

Go to Tigtag

Discover free online CPD for primary science from Reach Out CPD.

Go to Reach Out CPD