What You Need:
- Dead grass
- Home use microscope
- Fill the glass half way with water. If you are using tap water, let it sit overnight so most of the chlorine evaporates.
- Add a handful of dead grass to the water and sprinkle it with a pinch of yeast.
- Place the glass in a warm place overnight.
- Over the next week, look at drops of water from the glass under a microscope at a fixed time everyday. To do this, draw water from three different areas—the surface, the grass and the bottom of the glass.
- Within a day or two, you should start to see quite a few protozoa swimming around.
- Make notes and drawings of the organisms you see. You will also see sequential changes in the kinds of and number of protozoa.
Many of the the protozoa you see were living on the grass. When grass dies and dries up, the protozoa encyst (form a protective cyst around themselves). These cysts remain dormant for a very long time, waiting for rain or other water to make them active again. Other protozoa arrive through the air as cysts. Even the dust that collects on the furniture in your house is full of cysts. The yeast that you added is actually composed of tiny fungi that reproduce quickly. They feed on the nutrients from the dead grass and in turn, make excellent food for the protozoa. As the days go by, the changes in the protozoan population depends on the cysts present, their life cycle and conditions that are favourable for the growth of various protozoan species.