As an educator, it’s always nice to confirm that what you are doing in your classroom is preparing your students for the next level. The lesson plans, the products you teach with, the articles you read, the teacher education classes you attend, etc., are all key factors in your success. Keeping that in mind, we thought it would be nice to give you an inside look into some college level science courses. Whether you teach on the elementary, junior high, high school or college level, it’s always good to see what others are doing.This past month, the Science Scene Team took an exciting road trip as we had the opportunity to visit the beautiful campus of the University of Louisiana at Monroe. Dr. Sushma Krishnamurthy, the School of Sciences Director, was very kind to us by setting up not just one class visit, but two! We observed a Principles of Biology I Lab taught by William Futch and James Holt, as well as a Freshwater Ecology Field Lab taught by Dr. Anna Hill. Both were very impressive, to say the least!
ULM Principles of Biology I Lab
In the Principles of Biology I Lab, freshman students had the latest technology at their fingertips! Using a Vernier/Logger Pro Spectrometer to perform a spectral analysis of plant pigments, they extracted pigments from spinach and other plant samples to measure the visible absorbance spectra. Understanding the visible spectra of plant pigments is important because plants contain many different molecules directly or indirectly involved with photosynthesis, which may impart color to the plant. The specific mixture of chlorophyll molecules found in spinach absorbs several wavelengths of visible light in the blue and yellow-red range.
The combination of visible light that is not absorbed appears green to the human eye. Students also analyzed blue and yellow food coloring to compare with the plant pigments. The comparison gave a reference by which the comparative peaks or specific features of the spectrum of each could be seen. This measurement of the absorbance spectrum gave exact evidence of the pigments present in the plant extract samples. This study took the students deep into the concept and reality of photosynthesis and all the processes involved.
This class also has an ongoing experiment involving the discovery of local pond life (Pond in a Jar). At the beginning of the semester, students prepared a self-sustained ecosystem by preparing a jar with pond water - complete with plants and animals. They treated some jars with common pollutants, while others were left untreated. On a weekly basis, the students observe their experimental samples using their Ken-A-Vision Microscopes with Ken-A-Vision PupilCAMs to see what has originated and is thriving in their jars. The PupilCAMs are great for large numbers of students because they allow a group of students to see what is under the microscope at the same time without sharing the microscope’s viewfinder. One lab group discovered a nymph from their jar and shared it with us on the computer screen where we could all observe it moving, spinning, and breathing. Mr. Futch and Mr. Holt both say that their students find many expected specimens, but are also surprised to find unexpected discoveries, as well. With this Pond in a Jar experiment, students are experiencing a new awareness of their role as stewards of our environment.
ULM Freshwater Ecology Field Lab
As we left the Principles of Biology I Lab, we were excited to find that our next class, the Freshwater Ecology Field Lab with Dr. Anna Hill, would actually take us into the beautiful bayou that runs through the middle of campus. After meeting briefly in her classroom, Dr. Hill led her class across campus carrying all of the equipment required for the day’s activities.
After we checked out the canoes, Dr. Hill did an equipment checklist with her class to ensure all of the needed equipment was there, and also, so that nothing would be left behind when the field lab was completed. The list of products included: two YSI meters, a LaMotte Turbidimeter 2020, a secchi disk, two Oakton Waterproof EcoTestr pH2 Meters, a Plankton Net, an Ekman Bottom Dredge, Newark Testing Sieves, two dip nets, and each student had their own Rite in the Rain Notebook for logging their collected data.
Understanding the local environment and the specific ecosystems is at the top of Dr. Hill’s list of study for this class, so to begin, she gave us an overview of the parameters to be tested. Then, the class was divided up with the equipment to perform the tests. The students with the YSI meter were directed to measure the dissolved oxygen level within the bayou because it is very important to the success of the animal and plant life. Oxygen is continually produced by the aquatic plant life through photosynthesis, but temperatures can affect the concentration of dissolved oxygen in surface water. For instance, cold water holds more dissolved oxygen than warm water. During the lower temperatures of winter and early spring, the dissolved oxygen concentration is high. If the dissolved oxygen level declines below the normal range, the water quality is compromised, and organisms and plant life begin to die off. The students learned the importance of dissolved oxygen in the water and how it affects the plant and animal life of the bayou.
The next two groups were assigned the test of checking the water clarity, or turbidity. One group was given a secchi disk, while the other was given the LaMotte Turbidimeter 2020. The group with the secchi disk lowered the quadrant-marked disk deep into the water and then slowly reeled it in using the graduated rope toward the surface. When clarity was evident, they noted the depth on the graduated rope indicating at what level sunlight penetrated the water. The group with the LaMotte Turbidimeter 2020 used it to determine a quantitative measurement of turbidity. The turbidimeter measures the amount of light scattered at right angles from a beam of light passing through the test sample. This data extended and further defined the use of the secchi disk in determining the water clarity. Both of these tests were done as indicators of the presence and success of the photosynthetic process.
Another very important parameter to be tested was the pH level of the bayou, so a group of students used the Oakton Waterproof EcoTestr pH2 Meters to determine if the pH level was healthy or not. Most freshwater lakes, streams, and ponds have a natural pH in the range of 6 to 8. Increased acid levels result in harmful ecological effects if the pH of the aquatic system falls below 6 and especially below 5. As the pH approaches 5, non-desirable species of plankton and mosses may begin to invade, and populations of fish such as smallmouth bass disappear. Below a pH of 5, fish populations begin to disappear, the bottom is covered with undecayed material, and mosses may dominate near shore areas. Below a pH of 4.5, the water is essentially devoid of fish. Extreme pH levels are also damaging to the health of an aquatic system, causing adult fish and invertebrate life to die while also damaging the development of juvenile fish. The highly alkaline environment will strip a fish of its slime coat and can “chap” the skin of the fish. Performing this test, the students learned the importance of maintaining a healthy pH level for the overall life found in aquatic systems.
Next, Dr. Hill had her students use the Plankton Net, Dip Nets, and the Ekman Dredge along with the Newark Sieves to collect and view samples from the bayou. One set of students took the plankton net out into the middle of the bayou in a canoe to collect a sample of the macro-aquatic life swimming there. Examining the viewing tube of the Plankton Net, students could see little “swimmers” along with algae and some debris. Some students used dip nets along the shoreline to collect samples from the water’s edge. The samples were dumped into buckets for observations where students discovered a couple of tiny crayfish, along with algae and debris. The group with the Ekman Dredge took it out in the canoe to get a sample from deep down on the bayou’s bottom. Back on shore, they poured the collected sample into the Newark Sieves.
The sieves separated the mud from the small creatures, and students were excited to discover Ghost worms, blood worms, algae, and other exciting examples of the thriving life of the bayou. The presence of specific species brought into focus the ecosystem that is inclusive of shore, surface and the bottom of the bayou. The day concluded with all of the data being recorded in each student’s journal, and students left with a new awareness of the interrelationships between the fauna, flora, water and atmosphere, as well as the footprint of humans on the complex life of a bayou. Dr. Hill gave us a perfect example of how our understanding of the life that an aquatic system holds can impact our decisions of ecological stewardship.
