By Timothy Stewart, Janette Thompson, Kristina Tank, Makayla Buck, Anna Drahos, and Benjamin White
We are experiencing a global environmental crisis, exemplified by declining biodiversity and increasingly degraded ecosystems. Actions needed to produce healthier and sustainable social and ecological systems require ecologically-literate citizens with an interest in nature and concern for the welfare of both humans and non-human species. [1] , [2] , [3] Inquiry-based field ecology experiences can promote such literacy while also educating students about scientific procedures. [1] , [4]
In this article, we present an ecology activity that has been implemented with first graders in an informal park setting. This activity provides opportunities for students to investigate the relationship between habitat abundance and biodiversity, and learn how biodiversity benefits humankind. In this 45-minute lesson, students collect plastic toy arthropods from two types of 1-m2 plots located in a woodland and that differ in the abundance of leaf litter (dead leaves covering the ground). Students find that plots with abundant leaf litter, and therefore the most habitat, have the greatest abundance (numbers of individuals) and diversity (number of species) of plastic arthropods. With instructor guidance, students interpret causes for these results, learn an ecological concept, and develop a broader understanding for the importance of what they learned.
Activity procedures are based on the learning cycle model, which uses engagement, exploration, concept development, and concept application phases to teach scientific principles and their relevance. [5], [6] Our lesson was developed by a team of undergraduate students and pre-service science teachers enrolled in the Field Ecology Research and Teaching course (NREM 380; https://www.nrem.iastate.edu/fieldecology/) at Iowa State University [7] and was implemented at a local park through partnership with an elementary school. The teaching activity replicates methods and results from a research project previously completed at the same local park by this team of college students as an NREM 380 course requirement. In their research, students removed leaf litter from eight 1-m2 woodland sampling plots, and then returned leaves to four plots. Two weeks later, arthropod abundance and species diversity were highest in plots containing abundant leaf litter.
Preparing for the activity
Our activity is designed for a class of 24 students, divided into four groups of six children, and with one instructor overseeing each student group. Instructors prepare for the activity by first locating a woodland or stand of trees in a schoolyard or nearby park (Figure 1). Dense underbrush, poison ivy, or thorny plants should be absent or removed from the study site. Instructors create eight 1-m2 sampling plots in this wooded area, with the perimeter of each plot identified using stake flags and tape (Figures 2–3). Instructors remove dead leaves from the four “experimental” plots bordered by flags and red tape, but leave all leaf litter within four “control” plots surrounded by flags and green tape. Plastic toy arthropods (Figure 4) are used because living arthropods can be difficult to find and capture, are delicate and easily harmed, and may bite or sting when handled. Velcro® fasteners are glued to undersides of these plastic arthropods before they are placed in plots. To replicate actual arthropod behavior and habitat use, two or three different “species” (e.g., different toy shapes) and six to eight individuals are placed in each experimental plot. In the control plots with leaf litter, five or six different “species” of plastic arthropods and 12 to 16 individuals are placed under leaf litter.
Figure 1. Students and instructors gather in a woodland for the exploration phase of this activity.
Engagement phase
As students assemble at a central gathering area (e.g., a lawn adjacent to the woodland study site), an instructor attaches an illustration of a common carnivorous arthropod (e.g., spider) to an easel pad. Students are asked, “Do any of you recognize this animal”? What name have we given this creature?” After students respond, and the word “spider” is written underneath the image, an instructor asks, “Can anyone tell us where spiders live and what they eat?” Correct responses are again recorded under the spider image before repeating these procedures with a familiar herbivorous arthropod (e.g., grasshopper).
Students are then asked, “What is similar and different about these two animals?” By the end of this discussion, it should be clear to students that the spider, which feeds on other animals, and the grasshopper, which consumes plants, eat different foods. However, both animals are invertebrates with jointed limbs and exoskeletons, and are therefore arthropods. The engagement phase concludes by informing students that they are going to be scientists today as they search for arthropods in a woodland.
Figure 3. Students preparing to collect plastic toy arthropods from a plot with abundant leaf litter (control plot)
Exploration phase
The first graders are divided into four research teams, each consisting of six students that are supervised by one instructor. One student in each team is provided with a green cup, and another receives a red cup. As each team observes one experimental and one control plot, their instructor asks, “Do you notice anything different about these two areas of ground?” Students right away recognize that one plot is covered with leaves and the other has comparatively bare ground.
Instructors inform students that they will collect plastic toy arthropods from these two plots and explain why they will search for artificial arthropods instead of actual animals. Before sampling begins, rules are established to promote inclusive participation and empathy for living creatures. Instructors ask students to pretend that the plastic arthropods are alive, and then demonstrate how to handle them carefully. They also inform students that each team member may collect one plastic arthropod from each plot, and only then can those remaining be collected by whomever finds them.
During sampling, each team finds plastic arthropods in the plot surrounded by red tape (experimental plot) and transfers them to their red cup. Plastic arthropods are then removed from the control plot and transferred to their green cup. Instructors ensure recovery of all plastic arthropods while helping students search for them under leaves. Teams then return to the central gathering area. To report findings, we use a felt-covered poster board placed on an easel (data summary board, Figure 4). One side of the board is bordered by red tape and labeled “Fewer leaves,” thereby defining where findings from experimental plots are recorded. The other side, where results from control plots are reported, is outlined in green and labeled “More leaves.”
An instructor asks one student team to approach the data summary board with their red cup. Each team member removes one plastic arthropod from the collecting container and attaches it to the side of the board outlined in red tape (Figure 5). Teammates alternate attaching plastic arthropods to the board until this cup is empty. Instructors then ask a second team to bring their green cup to the board and use the same procedure to transfer all plastic arthropods to the section of the board outlined in green. Subsequently, a third team attaches contents from their red cup to the side of board outlined in red, and the fourth team attaches contents from the green cup to the appropriate side of the board.
At this stage, half of the data are recorded on the data summary board. Each team has one remaining container with plastic arthropods, including two teams with red cups and two teams with green cups. Because of time and space constraints, students do not attach remaining arthropods to the data summary board. When instructors ask students, “What do you notice here?”, it is clear that additional data reporting is unnecessary. Students recognize that the total numbers and diversity of plastic arthropods are highest in plots with abundant leaf litter. Instructors make findings relevant by explaining to students that the study they completed replicates an actual study of living arthropods.
Figure 4. Plastic arthropods attached to the data summary board, which illustrates that arthropod abundance (total numbers) and diversity (number of different species) are greatest in plots with abundant leaf litter
Concept development phase
In the concept development phase, instructors use a carefully planned question-and-answer discussion and record that information on an easel pad to help students interpret study results and learn ecological principles. Instructors ask students, “Why do you think we found differences in numbers and kinds of arthropods in plots with different amounts of leaf litter?” Drawing from their observations, students correctly respond that plots with many leaves provide more hiding places and therefore more arthropods. This provides instructors opportunities to introduce the term “habitat” and explain that as habitat abundance changes, we also see a change in the abundance of arthropods, and in the number of different kinds of arthropods. The follow-up question — “What else do arthropods need that might be more abundant in plots with leaves?” — helps students understand that good habitat provides many essential resources, including food in the form of living and dead plants (for herbivores and detritivores, including grasshoppers and beetles), and other animals (for carnivores, including spiders).
At this point, instructors introduce the term “biodiversity,” defined as the variety of living things (e.g., species), that inhabit an “ecosystem,” which students learn is any environment where plants and animals can live. Through exploration and discussion, students have learned that an ecosystem with good habitat has greater abundance and diversity of resources (shelter, food), and therefore higher biodiversity than ecosystems with poor habitat. This relationship between resource abundance and diversity and biodiversity is the primary ecological concept that this activity is designed to teach.
Figure 5. Students attaching plastic arthropods to the data summary board during the exploration phase of this activity
Concept application phase
In the final phase of this activity, students demonstrate a broader understanding of the concept they have learned by applying it in an extended context. Instructors ask students, “What do you think would happen to arthropod abundance and diversity if we removed all trees and other plants from our woodland?” Students predictably answer that arthropod abundance and species diversity would decline. When asked why they answered this way, students respond that animals would die or leave the ecosystem because habitat and food provided by fallen leaves would disappear. Instructors then ask, “Does it matter if arthropod abundance and diversity decline, and if so, why do you think it matters?” This question-and-answer discussion leads students to understand various ways that other organisms (insectivorous birds and bats, flowering plants) depend on arthropods for survival.
The activity concludes with “take-home messages” that arthropods are beneficial to humans, and that our behaviors affect them. Instructors inform students that arthropod abundance and diversity are declining all over the world (see sidebar) and then ask the audience, “Does this matter to you?” Responses to this question indicate that students have empathy for arthropods (e.g., “I would be sad if they disappear.”) and also understand their practical importance (e.g., eating pest insects, pollinating crop plants, decomposing dead organisms). This launches into a discussion about how resources in the form of living and dead plants must be available for arthropods to thrive, and that people can also help by killing only those arthropods that are a threat to human welfare.
Conclusion
This activity provides opportunities for children to learn scientific methods, gain ecological knowledge, and work collaboratively in a realistic outdoor setting. Consistent with the learning cycle model of teaching, this ecology field experience helps students learn how to collect data, interpret findings, learn an ecological concept, and apply knowledge to related environmental problems. Students enjoy both the exploration phase of this activity (searching for toy arthropods, attaching them to the data summary board) and interactive discussions. The lesson design also ensures ample opportunities to evaluate student learning as students respond to instructor questions during the various group discussions embedded throughout the lesson.
Timothy Stewart (associate professor, Department of Natural Resource Ecology and Management), Jan Thompson (professor, Department of Natural Resource Ecology and Management), and Kristie Tank (associate professor, School of Education) teach the Field Ecology Research and Teaching course (NREM 380) at Iowa State University. Tim also teaches introductory biology and field natural history courses and enjoys sharing his love of living creatures with students of all ages. Jan teaches college forestry and urban biodiversity courses that include exploration of a variety of ecosystems in different settings. Kristie works with preservice elementary teachers and teaches science, technology, and STEM methods courses. Makayla Buck, Anna Drahos, and Benjamin White designed and taught the activity described in this article when they were students in NREM 380. Makayla is currently a science teacher at Roosevelt Middle School in Cedar Rapids, Iowa. Anna recently obtained her Master of Arts in Teaching degree from Iowa State University. Benjamin is currently an educator at Blank Park Zoo in Des Moines, Iowa.
References
[1] Gallay, E., Marckini-Polk, L., Schroeder, B., and Flanagan, C. 2016. Place-based stewardship education: nurturing aspirations to protect the rural commons. Peabody Journal of Education 91:155–175.
[2] Schild, R. 2016. Environmental citizenship: what can political theory contribute to environmental education practice. The Journal of Environmental Education 47:19–34.
[3] NAAEE. 2019. Guidelines for excellence: K–12 learning. Washington, DC: North American Association for Environmental Education.
[4] Doll, A. 2021. Environmental education through humane education. Green Teacher 126:33–38.
[5] Marek, E.A. 2008. Why the learning cycle? Journal of Elementary Science Education 20:63–69.
[6] Olson, J.K. 2009. Being deliberate about concept development. Science and Children 46:51–55.
[7] Stewart, T.W., Thompson, J.R., Tank, K.M., Olson, J.K., Rentz, M.S., and Wolter, P.T. 2022. A course-based research and teaching experience for science majors and preservice educators (“Field Ecology Research and Teaching”). Journal of College Science Teaching 52:16–22.
Figure 2. Materials list, with justification, quantities, and approximate costs in United States dollars for a class of 24 students