Experiments

Creative Grow Buddies

The experiment begins with an activity in which the students make their own grow buddies. Grow buddies are stockings filled with a substrate (potting soil) and grass seeds. They are then tied off and marked or decorated. This activity is intended to stimulate student participation in science. The use of grow buddies will help to personalize science experiments for students of all grade levels. Grow buddies can be used to demonstrate the scientific method and experimental design. Depending on the subject and the level of the students, teachers can vary their approach to the experiment.

The teacher could design the experiment or let the students do it. The expanse of the experiment is only limited by materials and space available. The variables that could be manipulated are light, water, temperature,

nutrients, salinity, substrate, and species of plant to grow. In Project CYPRESS, we wanted to examine the interactions of flooding, salinity, and nutrient level (fertilizer) on rye grass seed germination and growth. The experimental design was a 2x4x2 factorial arrangement with two replicates, meaning that we had two levels of flooding, four levels of salinity, and two levels fertilizer. We made observations over time and collected data. Of course, we chose these variables because we are interested in wetlands ecology. You can choose different variables to fit your lesson.

Grow Buddy Experiment

Filter vs. Elodea

If you have aquaria, you can do some interesting experiments. The participants of Project CYPRESS designed a turbidity experiment. Clay particles were suspended in the aquarium water to create the turbidity. The treatments in this experiment were the use of man-made filters, plastic plants, real plants, and the combinations of these. The two types of real plants used were cabomba and elodea.

They were testing the capability of real plants to clean dirty water. The experimental design was a 2x4 factorial arrangement with two replicates, meaning that we had two treatments of man-made filters, four treatments of real and plastic plants. The participants measured turbidity and made observations regularly. They collected, graphed, and analyzed the data from their turbidity measurements. The real plants cleaned the water better than the man-made filters!!

Aquarium Observations

Food Preference

Other types of experiments could be done in the same aquaria; schooling behavior, animal / animal interactions, and plant / animal interactions. You could also turn your aquarium into a terrarium for even more possibilities. In another experiment, a terrarium was used to study the food preference of Lubber grasshoppers. Different types of vegetation were suspended from the lid of the terrarium by string. Twenty Lubber grasshoppers were caught and put into the terrarium. The participants made observations of the vegetation to determine which plant the grasshoppers prefer to eat.

Another aquarium experiment involves testing flood adaptations of wetland plants such as alligator weed, Alternathera philoxeroides. This is a good wetland plant specimen because you can easily find it in ditches. In this experiment, we have six identical pots of alligator weed we found in a "dry" ditch. We place three tiers of bricks in the aquarium to form three distinct levels. We place two pots at each of the three flood levels (extremely flooded, flooded, and moist but not flooded).

At the Beginning

At the End

Then we fill the aquarium with fresh water. As with any organism, the alligator weed will need to adapt to a change in its environment or it will die. Regularly, we make observations of the alligator weed. After some time, we notice the flooded alligator weed getting taller faster. In order to get oxygen to its roots, the stem will grow to penetrate the surface of the water. We compared the stems of the flooded plants to that of the moist but not flooded. The stems of the flooded plants were wider and hollow like a snorkel. This was the flood adaptation of alligator weed. Give it a try in your classroom and see if you get the same results.

There are several factors that affect decomposition; temperature, moisture, presence of oxygen, substrate type, and surface area. An important feature of wetlands is the soil type. Project CYPRESS participants wanted to find out at what level of wetland soil does decomposition occur the best on hot dogs. They each got a hot dog, made four cuts, placed it in a mesh pouch, and each was weighed and marked ( 32 total ). Then they decided they wanted eight different levels with four pouches in each level. The participants placed a layer of soil then a layer of four pouches until all eight layers of the pouches were buried. A meter stick was attached to the outside of the

Decomposition Tank

aquarium. Water was then slowly poured on the soil until it reached half way up the aquarium. The soil began to subside and this could be measured. Wetland soils are characteristically reduced and have strange

Measuring Redox Potential

chemical properties. This can be measured using wire probes and a millivolt meter. After several weeks they began measuring the soils redox potential (the availability of electrons). And a wetland soil profile had developed. After eight weeks, the pouches were collected, dried, and weighed. The weights were then compared to the weights taken before the pouches were buried. The difference in weight is the measure of decomposition. The bags were marked so that we can determined what layer provided the best conditions for decomposition. Be careful if you try this experiment, it can get kind of smelly.

These are brief summaries of some of the experiments participants of Project CYPRESS completed. We hope you can adapt them to your lessons and have some fun. If you have any questions, you can e-mail Ernie Simoneaux at esimoneaux@selu.edu .

This web page was designed by Shannon Martin.
If you have comments or suggestions, email me at sbm@selu.edu