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BIODOMES (using two-liter bottles)
Procedure:
1. Take the wrapper off and rinse the bottle thoroughly.
2. Cut top from the bottom and invert. If it is too loose,
then duct tape can be used around the edge of the bottom to thicken that edge so the
top won't fall down into the bottom.
3. Drill several holes in the bottle cap (will act as a
filter).You can also take a piece of felt and pull it through a larger hole in the
cap and let it dangle in the water below... hydroponic watering. (Really great over
long breaks)
4. Put soil and a plant in the top. Put water, aquatic plants,
(elodea, duck weed...)snail, and one guppy in the bottom. Let students decide if they want
a female (she might have babies.... fun but will there be enough food and oxygen, will mom
eat her babies?) Students enjoy the fact that snails are hermaphrodites so that many times
the lone snail will lay eggs on the side of the bottle. I usually can get the "nuisance" pond
snails (little black snails) for free from pet stores but they are getting harder to find.
5. Place by a well lit window or use a shop light with the lights
between 8 -12" away from the biodome. If using artificial light be sure to have a timer and vary
the duration according to the plants used. Most plants will grow well with 12 hours of light.
Simulated Environmental Changes:
The class should simply observe and record changes in their jars. Over time you may introduce an
environmental change in some jars. You can:
- increase the amount of artificial light
- add lemon juice ( acid rainfall)
- cold versus warmer temperatures
- add salt ( winter road salt)
- add detergent, or vegetable oil...
- colored cellophane around jars to test growth under different colors of light
- what about different color of original bottles such as green versus clear?
- impact of different soils above the water such as clay,sand,humus...
- experiment with what plants grow well in a shallow dish, may even lead to Bonsai growing
* Important to stress keeping a daily journal, changing one variable only, and have them make
an hypothesis for each experiment
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