Microorganism
Microorganism is a tiny living thing too small to see without a tool like a microscope.
Your kitchen is full of microorganisms you cannot see. A jar of yogurt holds billions of tiny bacteria — each one smaller than a speck of dust. They eat the milk sugars and turn the milk thick and sour. Without a microscope, you would never know they were there.
Explaining microorganism by grade level
A drop of pond water looks clear, but it is full of life. If you use a strong lens, you can see tiny things that swim and move. Some look like dots. Some have tails and zip around in the water.
Projects that explore microorganism
Soil contains huge populations of microorganisms — tiny living things too small to see without a microscope. In this experiment, these invisible decomposers break down buried carrot pieces at different speeds depending on temperature and moisture. Some work with oxygen. Others are anaerobic bacteria that work without oxygen and can decompose food just as fast.
A single drop of pond water holds microorganisms — tiny living things invisible to the naked eye without a microscope. Under magnification, some prove to be single-celled protists with a nucleus. Others are multi-cellular. Using a key of freshwater microorganisms, you identify and classify each one. The diversity in one drop shows how many tiny living things share a pond ecosystem.