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KS3: Useful Microbes

In this lesson, students learn that microbes can be useful, experimenting with Lactobacillus and Streptococcus to make their own yoghurt.

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Learning objectives
All students will:
  • Understand that some microbes can be put to good use
  • Understand that we need bacterial colonisation to live a healthy life
Most students will:
  • Understand that we need to protect our normal microbial flora
Background Information

Bacteria are single-celled organisms and although some of these cause illness and disease, others are helpful and useful. One of the main ways in which bacteria are beneficial is in the food industry. The natural by-products created during normal microbial growth are used to make many of the food products we eat everyday.

Fermentation causes a chemical change in foodstuffs. It is a process by which the bacteria break down the complex sugars into simple compounds like carbon dioxide and alcohol. Fermentation changes the product from one food to another.

In this lesson plan, students learn how fermented microbes are used to create food products and the conditions they need to grow and multiply quickly.

Main activity:
  • Yoghurt experiment
Extension activities:
  • Microscopic yoghurt
  • Food production poster
Curriculum links


  • Health and prevention


  • Working scientifically
  • Scientific attitudes
  • Experimental skills and investigations


  • Structure and function of living organisms
  • Cells and organisation
  • Nutrition and digestion
  • Material cycles and energy
  • Cellular respiration


  • Reading
  • Writing
Supporting Materials
Teacher sheets
KS3 Useful microbes teacher guidance
Student worksheets
SW1 Yoghurt experiment
SW2 Microscopic yoghurt
Student handouts
SH1 How to make yoghurt instructions