Ecosystem Explorations

By Eve Pranis

"Our sixth grade curriculum required us to cover concepts dealing with growth needs, adaptations, and ecosystems," reports Pocatello, ID, teacher Mary McAleese. "So we decided to bring in some live plants to explore up close." Since the classroom was short on light, Mary solicited donations from local plant businesses of tropical plants adapted to low-light conditions on rainforest floors. Before long, the students transformed the classroom into a 40-square-foot rainforest -- a centerpiece for plant and environmental studies, complete with a floor-to-ceiling canvas backdrop.

Silk vines donated by a local florist and real liana vines donated by a grandmother hung from the canopy. Inspired by a "Sounds of the Rain Forest" recording, students researched, then created paper mache creatures to dwell in their forest. A plastic shower curtain on the floor covered with soil and compost became a laboratory for hands-on plant investigations, including testing the effects of "acid rain," propagating plants from leaves, comparing decomposition rates in moist and dry environments -- even growing moss on different surfaces.

"Although we started with a more 'exotic' ecosystem, the classroom rainforest environment triggered an interest in nearby ecosystems," says Mary. "Students compared their classroom-simulated ecosystem with local environments, and became more enthused about exploring the global garden."

No Plant Is an Island

Growing bean plants on the windowsill or marigolds for Mother's Day are experiences that allow students to explore the growth needs of individual plants. In the environment outside the classroom, however, plants don't exist in isolation, but are all part of the great web of life in which all living things constantly interact with other living and nonliving components of their environment.

Whether you're growing in a classroom light garden, in the school yard, or in an outdoor garden, you can engage students in exploring plants in the context of the communities and ecosystems of which they are a part. Transforming your classroom into a rainforest is but one way to get there. Consider launching a project that gets students exploring close to home. You might, for instance, start simply by inviting students to observe and keep records of plant/animal interactions in your GrowLab, outdoor garden, or even in a square foot of lawn. A classroom earthworm farm can provide a compelling centerpiece for exploring the role of decomposers in recycling nutrients in an ecosystem. Or your students might launch a more complex project, such as recreating a prairie community on the school grounds.

Students may choose to focus broadly or to concentrate on specific interactions between plants and other living things -- exploring the relationship between bean plant roots and nitrogen-fixing bacteria, aphids and their feeding preferences, or butterflies and their host plants, for example. Studying plant characteristics (such as leaf shapes and textures) can help students focus on plant adaptations to specific environmental conditions. Simple plant growth investigations can help students discover on a small scale how a change in the physical environment (e.g., temperature, pollutants, or water) affects plants. And mini-ecosystem simulations (see below) can help underscore concepts such as interdependence by demonstrating how removing one organism can affect everything else.

Here are a few of the ways in which students in our growing network have explored plants in their environments.

Ecosystems, Up Close

"My fifth graders had been studying ecosystems and got curious about trying to simulate some in the classroom," reports Tenafly, NJ, teacher, Marie Catania. "We ended up settling on trying to simulate rainforest, desert, and boreal forest ecosystems using 10- and 25-gallon tanks from a pet store and recommended plants from a science supply catalog."

Small student groups each set up and focused on one type of ecosystem and had ample time to observe, wonder, and reflect, before they did any in-depth research. Students made daily observations and measurements, and created double-entry journals, she reports, in which they'd describe observations on one side of a page, and questions and wonderings on the other. "When students began to question what types of animals could live in the different ecosystems," she adds, "I encouraged them to research to find out the types of animals that might be found in each. They had to learn enough about the animals to feel comfortable that they could introduce and care for them in the classroom ecosystems." A trip to a local pet shop turned up such creatures as tree frogs for the rainforest and chameleons for the desert.

To sustain their ecosystems, Marie's students did thorough research and came to understand some key concepts -- about water cycles, plant adaptations, and interactions, for instance -- once they had to apply them. She adds that one student, curious to find out what others in the school knew about different ecosystems and the threats they faced, created and conducted a schoolwide survey. "My kids were surprised to realize how many misconceptions existed, so they set up a time to present their research and share their classroom ecosystems with the rest of the school."

Although the class imported many of the plants and animals in their simulated exotic environments, Marie reports that this experience sensitized students to ecosystems closer to home. "The students began to notice an unusual green growth in a pond near school property, and were inspired to contact local biologists and to research directly what the cause might be."

Inquiring Pen Pals Want to Know

"We'd been studying Arizona and what physical factors make it unique," reports Phoenix, AZ, teacher Kathleen Maledon. "I wanted my sixth graders to develop a sense that the physical environment and climate in different parts of the country have a big impact on the types of plants that could survive. A friend who teaches in Michigan agreed to collaborate, so we launched a pen pal plant experiment exchange."

Students from each area brainstormed seeds and plants they could send to their pen pals, then thought about questions they might ask their plant buddies to experiment with, such as How will the soil, temperature, rainfall, and other factors in your region affect the growth of plants from our region? Once students had chosen questions, they designed experiments and predicted results. They completed "Buddy Experiment" sheets to send with their pen pal letters detailing what materials they were sending, their experimental question and prediction, and the procedure, including records their pen pals should keep.

The students also researched and charted temperatures, rainfall, and other climatic factors for each region. Since one of the biggest differences the kids discovered was the amount of rainfall, many of their experiments were water related, says Kathleen. When her students received boxes with plant materials and instructions from their pen pals, they could choose to conduct their experiments at home or school.

The experimental results that students sent back included photographs and letters that reported findings and confirmed or refuted the other students' predictions. "Most things worked out very differently than the kids had predicted," notes Kathleen. "For instance, the Michigan students didn't realize how quickly water evaporates here, and some of their instructions didn't include enough water for plants adapted to more temperate conditions. Or kids discovered that they hadn't given accurate instructions on how to run the experiment, and their buddies pointed out which variables their peers hadn't considered." In many cases, results that conflicted with predictions provided fertile ground for discussing differences between regional climatic environments and ecosystems, says Kathleen. "But while their science skills and understanding of plant adaptations to different environments improved, the real bonuses were the communication skills and friendships that blossomed during the exchange."

Mini-Ecosystem: Biosphere in a Bottle

What insights can a jar full of mud and water give us about life on planet Earth? A humble jar of pond water can act as a "microcosm" of a larger system, similar in makeup and function. It will contain producers (algae and possibly higher plants), consumers (tiny animals), and decomposers (bacteria and fungi). Carbon, oxygen, and other important elements cycle through the mini-biosphere as in the larger world through photosynthesis, respiration, and decomposition. Windowsill or fluorescent lights can provide energy. These mini-ecosystems can provide a focus for long-term observation, an understanding that systems cycle and change over time, and a glimpse into the tremendous diversity of life -- even in a jar of pond water.

Carol Bacig and her sixth graders in Duluth, MN, were inspired by the "Biosphere in a Bottle" story (see related articles). Using silty mud and local pond water, each student filled and sealed his or her own biosphere jar and placed it on the windowsill. Regular observations kept students engaged as jars came to life with a diversity of plant and animal life.

Several students wondered how light would affect their mini-biospheres, so they experimented by leaving three jars in the light and putting three in the dark. Other students tested the pH of the water, then investigated how the biospheres would be affected by increasingly acid conditions. "We've even tied the biosphere project into our art and writing," says Carol. "After viewing the pond water under microscopes, I had students design an abstract art project based on what they saw. For a creative writing assignment, students imagined and described being dropped into this ecosystem."

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