Main idea

Microbes are tiny organisms that are too small to be visible to the naked eye. However, there are ways to make them visible even without having a microscope at hand. Species of microbes that naturally live in a river play an important role in the self-purification ability of a river. They live in water, on the surface of stones, pebbles and plants, and in the mud of a river’s bottom. They develop their communities according to the quantities of light, oxygen, and nutrients.

Goal

To show the students that even though they are invisible to the naked eye, species of microbes live everywhere in water environments, adapted to conditions with or without light, with or without oxygen, with plenty or almost zero nutrients. In rivers, they form a biofilm on the surface of stones, called periphyton, that is composed of various species of bacteria, algae and other microorganisms.

Concepts

microbes ®  periphyton (bacteria, algae and other microorganisms);

Introduction: What are Microbes and Where Can We Find Them?

Together with students, try to find out what kind of microbes they already know. There are dangerous (e.g., salmonella bacteria, etc.) as well as harmless microbes. Some microbes can cause deadly diseases, while without others life would not be possible. Even in our own bodies, numerous harmless microbes live in our intestines that help us digest food and create nutrients that our bodies need.

Activities in this lesson

Making a home for microbes
3.2.1
Subject: Art and craft, Biology, Chemistry
Age group: 10 - 12, 13 and up
Type of activity: Experiment, Field activity
Number of participants: Paired, Team
Discover Bacteria
3.2.2
Subject: Biology, Language
Age group: 13 and up
Type of activity: Debate, Experiment, Field activity
Number of participants: Team

Discussion: Microorganisms

Discuss what they learned.

Since microorganisms are very sensitive to nutrients and other chemicals in water, they can be good indicators of conditions in the water (pollution, quality of water, etc.). Explain what an indicator is.