Essential Science for Teachers: Life Science
Energy Flow in Communities Featured Classroom: Melissa Minnick, Walkersville, MD
Melissa Minnick, Walkersville, MD
“I think that when we teach life science with a hands-on constructivist method, we will bring these children’s world to them. Then they start to make the connections that we want them to make. Then they start to do that investigative thinking and that scientific thinking, and make the connections from what they see in their world to what they’re doing in the classroom, and realize that science is all around them.”
School at a Glance:
Glade Elementary School
- Location: Walkersville, MD
- Enrollment: 588
- Students per teacher: 16.7
3% African American
- Percentage of students receiving free or reduced-price lunch: 6% versus a state average of 37%
Melissa Minnick teaches fifth grade at Glade Elementary School in Walkersville, Maryland. Located 50 miles west of Baltimore, Walkersville is a small, middle-class community. The students at Glade Elementary regularly exceed the state average on state tests.
Melissa remembers how influenced she was by an early teaching experience: “When I was seven years old, I was at a babysitter’s, and I helped a child understand subtraction as backwards addition, and when the younger child understood it, I realized that that’s what I wanted to do with the rest of my life. So, all through high school, all through college, that’s what I worked on, becoming a teacher.” It’s not surprising then, that Melissa finds the moments when she gets to watch students “grasp a concept” the most rewarding.
Lesson and Curriculum
Communities; SCIS 3+
Lesson at a Glance:
Curriculum: SCIS 3+, Lawrence Hall of Science, Delta Education
In the weeks before the activity in Session 7, Melissa introduced her class to the idea of the interdependence of species. They looked first at food chains, then moved onto a more accurate model, the food web.
As an introduction to the unit, Melissa’s students posted the name of an organism on their shirt and, using yarn, connected themselves to organisms that either ate them or that they would eat. The class role-played hypothetical scenarios: if the student playing “X” organism sat down—“died”—what other species would be affected? Whoever else was connected to them also had to sit down. By running more scenarios, the class started to understand the idea of interdependence. For example, what if all plants died? The whole class sat down.
Melissa’s students also built a terrarium with each student maintaining a Communities Chart to track the feeding relationships inside. Early on, the terrarium contained only a few organisms and amounted to a straightforward food chain, as did their charts. As they continued to add things to their terrariums, their charts become more complicated. For example, when crickets were first added to the terrarium, their only food source was mustard seeds; when the class added bran, however, the crickets had a choice.
Each time something was added, the students watched for its impact and recorded it on their chart. Likewise, when Melissa introduced the idea of decomposition to the class, they added molds and bacteria to their charts. At the time of the taping, the terrariums were fairly complex with Communities Charts to match.
The featured activity involved the students in identifying the creatures in their terrariums as “producers,” “consumers,” or “decomposers.” They began by observing their terrariums and discussing in groups what they were seeing. Then, the students recorded their observations, questions, and predictions in their science journals, which they maintained on a daily basis.
A class discussion followed about what they were observing, and Melissa reminded them of the terms. Using labels with the words “consumers,” “producers,” and “decomposers,” the students attached the terms to the appropriate groups on the charts. They repeated the activity as a class, keeping their own completed charts.
The goal of the unit was for her students to build their understandings of the key properties of communities – that energy flow is the connecting piece that ties a community together and that organisms depend on each other for survival.
Reflect on Your Teaching
Students build and maintain a terrarium.
Students observe and describe feeding relationships among organisms in a terrarium.
Students construct food chains and webs based on observations.
Students apply the terms “producer,” “consumer,” and “decomposer” to organisms in a community.
Students describe energy flow through communities.
Consider the goals for this lesson as listed above. How can you create a lesson appropriate for your classroom that will fulfill similar goals?
Session 1 What Is Life?
What distinguishes living things from dead and nonliving things? No single characteristic is enough to define what is meant by "life." In this session, five characteristics are introduced as unifying themes in the living world.
Session 2 Classifying Living Things
How can we make sense of the living world? During this session, a systematic approach to biological classification is introduced as a starting point for understanding the nature of the remarkable diversity of life on Earth.
Session 3 Animal Life Cycles
One characteristic of all life forms is a life cycle — from reproduction in one generation to reproduction in the next. This session introduces life cycles by focusing on continuity of life in the Animal Kingdom. In addition to considering what aspects of life cycles can be observed directly, the underlying role of DNA as the hereditary material is explored.
Session 4 Plant Life Cycles
What is a plant? One distinguishing feature of members of the Plant Kingdom is their life cycle. In this session, flowering plants serve as examples for studying the plant life cycle by considering the roles of seeds, flowers, and fruits. A comparison to animal life cycles reveals some surprising similarities and intriguing differences.
Session 5 Variation, Adaptation, and Natural Selection
What causes variation among a population of living things? How can variation in one generation influence the next generation? In this session, variation in a population will be examined as the "raw material" upon which natural selection acts.
Sessions 6 Evolution and the Tree of Life
Why are there so many different kinds of living things? Comparing species that exist today reveals a lot about their relationships to one another and provides evidence of common origins. This session explores the theory of evolution: change in species over time.
Session 7 Energy Flow in Communities
Communities are populations of organisms that live and interact together. The structure of a community is defined by food web interactions. The process of energy flow is the focus of this session as the interactions between producers, consumers, and decomposers are examined.
Session 8 Material Cycles in Ecosystems
Studying an ecosystem involves looking at interactions between living things as well as the nonliving environment that surrounds them. Life depends upon the nonliving world for habitat, as well as energy and materials. In this session, material cycles will be explored as critical processes that sustain life in an ecosystem.