KS3: Useful Microbes In this lesson, students learn that microbes can be useful, experimenting with Lactobacillus and Streptococcus to make their own yoghurt. Scroll down for more information and to download resources. Download the complete lesson Understand the beneficial roles of microbes, including how bacterial colonisation supports a healthy body and the importance of protecting our natural microbial flora. Bacteria are single-celled organisms and although some of these cause illness and disease, ot...