Experimenting with changes


Surry Village Charter School students used several strategies in hopes of improving their biospheres’ car- bon and/or water cycles. Some students added a scoop of soil because they thought that more respiring organ- isms would help raise their biosphere’s carbon dioxide levels. Some students added new plants to support pho- tosynthesis. A couple of students added water to help jumpstart their dry biosphere’s water cycle; whereas, another pair added living plants, thinking that more plants would remove water from their saturated soil.


Systems “The biospheres were in an enclosed space, so we had to


make sure that there was oxygen for the animals to live. So, we learned about systems because we had to have water,


plants, and animals. We had to have plants to give out oxy- gen, animals to give out carbon, so it all balances out.” – Chloe, Surry Village Charter School 7th


-grader


On the first day of the Biosphere Challenge, students create a system that sustains life. Understanding systems is critical for understanding climate change. A system is when the whole of something is greater than the sum of its parts. A pile of dirt, plants, and rocks laying on the ground is not a system. When the parts are assembled into a biosphere that can sustain mul- tiple generations of crickets, spiders, or millipedes, then the biosphere is greater than the sum of its parts. The smaller components in the students’ biospheres — like the plants, insects, and soil — are smaller systems nested in the larger system of their biosphere. The climate change problem centers on the fact that


humans are making changes to smaller systems — through deforestation or burning fossil fuels, for example — which changes the larger earth system in ways that humans have never done before. When a smaller system changes, it may not cause an


immediate change in the larger systems that it is a part of, but those changes can add up and eventually have larger impacts. Most systems in nature tend to stay balanced, but because everything is connected, seemingly small changes can add up to cause larger changes. In a sealed 10-gallon terrarium, small changes can have big consequences.


Cycles “I didn’t know a lot about cycles before. I didn’t really


think about how things would pan out and, I guess, the long-term effect of things.”


– Joslin, Surry Village Charter School 8th -grader


Carbon is the backbone of life on Earth; however, it is exceedingly difficult in the classroom to represent the differ- ent ways it moves through our Earth system. To address this, we challenge students to illustrate the small-scale water and carbon cycles happening in their mini-biospheres. Students each create desk-sized cut-out illustrations revealing their understanding of the cycles occurring in their biospheres, and then superimpose their understanding directly onto the exterior glass walls. To close their day of playing with the notion of cycles, students are invited to make one change to help either the carbon and/or water cycle in their biospheres and then track its success over the following week using the CO2


meter. When cycles are balanced, matter doesn’t build up in


the 400ppm in the atmosphere. Why? The answer lies beneath the surface of the soil. Some sci- entists estimate that there are more than a million microor-


one part of the Earth system because it is cycled out just as quickly as it is put in. However, dramatic change in one part of a cycle can put the whole cycle out of balance. This is the dilemma with burning fossil fuels and releasing unprec- edented amounts of carbon dioxide into the atmosphere. Although fossil fuels are not burning in students’ biospheres, they soon observe that their CO2


levels are much higher than


ganisms in a teaspoon of soil. In our Earth system, the CO2 respired by these organisms is photosynthesized by the pleth- ora of plant life, so the cycle remains balanced. However, in our tiny biosphere systems, this cycle is likely to be out of balance due to its small size and the unnaturally large soil microorganisms-to-plants ratio.3


To see this first-hand, stu-


dents can be invited to use a smart phone with a magnifying feature (flash on), allowing them to observe a far greater num- ber and diversity of creatures than what students will ever see on just the surface of their biospheres. Healthy biosphere soils can reveal a maze of interconnected tunnels and passageways made and used by millipedes, roundworms, mites, beetles, and bacteria — and that’s just what’s revealed in the soil rest- ing directly against the glass wall. This magnifying tool can open a window into the extraordinary numbers, diversity, and activity of creatures that live beneath our feet.


Green Teacher 122 Page 15


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