Microorganisms
Microorganisms are tiny living things too small to see without a tool like a microscope.
A jar of yogurt holds billions of tiny living cells. Each one is far too small to see on its own. A thousand of them side by side still fit on a pin tip. The jar looks plain, but inside it is packed with hidden life.
Explaining microorganisms by grade level
Your hands pick up tiny living things all day long. They are too small for your eyes to see. If you press your finger on a food gel plate, they grow. After a few days, you can see small dots where they grew.
Projects that explore microorganisms
They live on your skin and on everyday objects, but they are too small to see with your eyes alone. Press your fingers or a penny onto a nutrient agar plate, and those invisible organisms multiply over several days into visible clusters called colonies. The variety of colonies — some looking alike, others very different — shows just how many of these tiny living things surround you all the time.
Insects carry microorganisms on their bodies, tiny living things too small to see without a tool. When you release each insect onto a petri dish filled with agar, those invisible bacteria grow into colonies you can measure over five days.
Door knobs, keyboards, water cooler handles — you touch these surfaces every day without seeing what lives on them. Swab five common surfaces, transfer each sample to an agar petri dish, and after five days the bacteria colonies that grow tell a clear story. Some surfaces hold far more bacteria than others, and the results are not always what you would expect.
A single scoop from a local pond can hold organisms from several major kingdoms of life. Prepare a wet-mount slide and work up through the magnification settings on a compound microscope — tiny organisms appear, darting and drifting across the slide. Sketching at least 10 of them and noting their size, color, and movement reveals just how diverse life can be in one small drop of water.