An inquiry into honey and pollen
by Leah Latshaw
“What is honey?” “Why is it different colors?” “How is the honey produced by a local beekeeper different than the honey found in the store?” These and many more questions were asked recently by Capital University students enrolled in a course I teach titled Science by Inquiry. The course focuses on inquiry based learning in which students get to ask questions and develop methods to answer those questions all while the instructor supports the learning with materials and scientific methods. Students enrolled in the course are all majoring in education and plan to become elementary teachers, middle school teachers or intervention specialists after graduation. It was the students’ questions at the beginning of the semester that led to the collaborative development of classroom learning experiences focused on familiarizing students with beekeeping, learning about current events, and then carrying out a simple pollen analysis using honey samples.
Some of the various honeys chosen by students for the pollen analysis.
Beekeeping and local food are hot topics, even in non-beekeeping circles. When my students began asking beekeeping-related questions, an invitation was extended to Dr. Joe Latshaw of Latshaw Apiaries LLC. (It is convenient that Joe is my husband, and I think this helps him find time to work us into his schedule.) Joe came and spoke with the class about beekeeping and his extensive research of behavioral genetics and honey bees. It was motivating for the students to hear a professional beekeeper share about the science of beekeeping and also about the commercial beekeeping industry. This was also enlightening to the students who had no firsthand experience with beekeeping on either the hobbyist or commercial level. The presentation was supplemented with six hands-on learning stations prepared for the students where they could learn more about various aspects of beekeeping. Each station presented a question that the students could answer using the materials available at that learning station. For example, the question “What does honey taste like?” was asked at one station where numerous honey products were available for tasting, including comb honey and honey of different colors and floral sources. Students were surprised by the substantial differences in color, flavor, and texture that they had never noticed or paid attention to before. The five remaining stations also had their own unique questions:
- How are queens, workers, and drones alike and different? Sample photos and diagrams were provided for each.
- What is inside a bee hive? An active observation hive was available for students to study.
- What does pollen look and taste like? Pollen samples were available for tasting. Prepared slides of pollen grains were viewed using a compound microscope.
- What equipment is used in beekeeping? Numerous tools such as a smoker, hive tool, frames, and a small demonstration hive were on display.
- How much more concentrated is honey than nectar? Three glass jars with lids were prepared ahead of time with sugar solutions of 20% (representing nectar), 50% (representing an intermediary), and 80% (representing honey).
To enhance understanding of the industry, students were encouraged to seek out current events articles related to beekeeping. The articles selected included topics such as honey smuggling, ultrafiltration of honey, and pollen identification. Students were challenged to keep asking their own questions related to their specific wonderings, and they were able to answer these questions with the help of many online resources. Classroom activities continued to be guided by students’ questions. The focus of many questions centered around honey and what is actually in the honey we eat. As an instructor, my challenge was to develop appropriate classroom activities that could help students try to answer their questions, but were also manageable for the students to apply. When asking whether the honey they were eating actually contained pollen, it was apparent that a simple technique was needed for removing pollen from honey samples and examining it under a microscope. The goal for using a simple method was to eliminate the need for using potentially hazardous chemicals that would prevent the students from replicating the activity in a classroom with middle school or elementary students with just minor modifications. Students’ curiosity about available honey sources led them to choose many different samples to include in the study. Some of the honey selected was labeled as local, raw, or organic. Other honey came from commercial honey packers and restaurants, primarily fast food establishments such at Popeyes, Kentucky Fried Chicken, and McDonalds.
Andrew Rutsky studying a slide prepared from one of the honey
samples.
In order to successfully examine the pollen, the pollen in the sample must first be concentrated and then stained to provide adequate contrast for viewing. While pollen contained in honey can be visible under magnification with no staining, it is beneficial to use a stain to make the pollen grains more readily visible for the students and to make the surface structure of the pollen grains more distinct. This was found to be most advantageous especially considering the low amounts of pollen found in some samples. To prepare the stain ten grams of gelatin were added to 35ml of distilled water in a glass beaker. The beaker was placed on a hot plate until the gelatin dissolved, stirring as needed. Next, 30ml of glycerin was added along with a few crystals of basic fuchsin stain to give it a rosy color. It was then poured into two sterile petri dishes. Once cooled, the plates were kept under refrigeration until needed. The stained gelatin was prepared in advance, and the two petri dishes that resulted were more than enough for preparing all necessary slides made in class.
The preparation of the slides required patience and appropriate equipment. Using methods adapted from Rex Sawyer, two slides were prepared by students for each honey sample they selected to analyze. First, clean slides were labeled for the appropriate sample being prepared. Students measured 10ml of distilled water into a small beaker. The beaker was placed on a hot plate until the water was warm but not boiling. Five grams of honey were added to the warm water and swirled until combined. Half of the sample was poured into each of two test tubes. These test tubes were centrifuged for a minimum of 15 minutes at a speed of 2,000rpms. After centrifugation, the test tubes were very carefully inspected for a small deposit of sediment near the bottom of the tube. It was found that some samples did not have a visible sediment and these were centrifuged a second time. It was often helpful to hold a white sheet of paper behind the test tubes to make it easier to see any sediment. When sediment was visible, a long sterile pipette was used to collect the sediment with as little of the solution as possible. This sediment was then gently spread onto the center of one of the previously labeled slides. This was done for each test tube, resulting in a total of two slides. Both slides were placed on a hot plate set to the lowest setting. This allowed the material on the slides to dry. Once dry, a small cube of the fuchsin stained gelatin was placed on the dry sample. The heat from the plate quickly melted the gelatin and the slides were immediately removed from the hot plate and covered with a coverslip. Now the slides were ready to be viewed using compound microscopes.
Abundant pollen grains found by students in a honey sample (400x).
Looking at the prepared slides under the microscope was intriguing. The first challenge was distinguishing pollen from what the students referred to as “debris.” In some instances, the debris would also pick up the stain. Having resources available in the classroom with photos of common pollen grains was helpful, and students often used the irregular amorphous shape of the debris as a distinguishing factor. When pollen was found most students selected several random places on the slides at which to count pollen grains. For samples containing larger amounts of pollen, this method was successful in providing comparative data for the different honey samples. In a few cases, the students had so much pollen that great care had to be taken to accurately count all the grains. Most slides were initially analyzed at a magnification of 100x. Individual grains could be more closely studied at 400x. Photos were frequently taken to document student findings using a camera with a microscope eyepiece adapter. Students also discovered that some samples contained very little pollen at all. In these cases the students changed their approach and scanned the entire slide in search of any pollen grains. These pollen grains were then counted and photographed, often times individually.
Considering the variety of samples chosen by the students, it was no surprise that there was a great deal of variation in the results. This is okay, after all, it is the experience that is most important and for the students to see that science can be messy and unpredictable. It was exciting to see students really taking on the traditional roles of scientists – comparing results with other groups, questioning their own results, looking for sources of error, and trying to make sense of their data. The creation of two slides from each sample was helpful in checking data for reliability. In one case, considerable pollen was found on one slide while very little was found on another slide from the same sample. This led students to question their work and whether the slide with little pollen was actually prepared correctly. More practice preparing slides could help improve their skills and the overall reliability of the data collected. After quantifying the pollen, attempts were made to identify the source of the pollen grains present in the various honey samples. At first, students tried to use text resources provided in class. With so many initial similarities in the appearance of some of the pollen grains, a new approach was devised. A list of common flowering plants that would be visited by honey bees in central Ohio was constructed. Images were found online of the pollen grains from these plants. Students then compared their samples with the images from this list. This proved more successful in helping the students create positive identification of the pollen grains. It also reduced the frustration that was easily created by having students blindly searching for matching images. Of course it was still challenging to positively identify the pollen in samples that came from other locations. The honeys identified as monofloral were easier to investigate as images of the pollen from the monofloral source could be found online and then compared; much like was done with the other local samples.
Using inquiry in the classroom allowed students to ask questions about bees and honey that were interesting to them. We then collaborated to find answers to those questions. Armed with new information and a wealth of experiences, students were challenged to present their new knowledge in a culminating poster session where we were able to celebrate their learning. Students shared their results with their classmates and guest judges, Dr. Joe Latshaw and Mr. Dana Stahlman, a successful and well-respected beekeeper in the local area. Students also responded to questions from the knowledgeable judges that helped them better understand honey bees, the beekeeping industry, and even our culture as it relates to business and economics. During this poster session students also reflected on the learning process and how this process could be used in the future in their own classrooms. Many students noted their increased awareness as consumers of honey products and their greater understanding of the beekeeping industry in general. The entire experience was a terrific learning process for both the students and the instructor alike. It will be exciting to build upon these basic skills and continue to encourage students to seek out answers to the questions they have about bees and honey.
RESOURCES
Berfield, Susan. “The Honey Launderers: Uncovering the Largest Food Fraud in U.S. History.” Bloomberg Business Week. Bloomberg, 19 Sept. 2013. Web. 15 Sept. 2014. http://www.businessweek.com/articles/2013-09-19/how-germany-s-alw-got-busted-for-the-largest-food-fraud-in-u-dot-s-dot-history.
Moore, Peter D., and Judith A. Webb. An Illustrated Guide to Pollen Analysis. New York: Wiley, 1978.
Parrish, Judy. “Pollination Ecology: Field Studies of Insect Visitation and Pollen Transfer Rates.” Teaching Issues and Experiments in Ecology. Ecological Society of America, 15 Aug. 2004. Web. 15 Sept. 2014. http://tiee.ecoed.net/vol/v2/experiments/pollinate/description.html#fuchsin.
Sawyer, Rex. Honey Identification. Ed. R. S. Pickard. Cardiff Academic, 1988.
Schneider, Andrew. “Tests Show Most Store Honey Isn’t Honey | Food Safety News.” Food Safety News. 7 Nov. 2011. Web. 15 Sept. 2014. http://www.foodsafetynews.com/2011/11/tests-show-most-store-honey-isnt-honey/#.VIOztjHF_zC.
Tschudy, Robert H., and Richard A. Scott. Aspects of Palynology. New York: Wiley-Interscience, 1969.
