BIG IDEAS, ESSENTIAL QUESTIONS and KEY CONCEPTS from OUR GARDEN to TABLE CURRICULUM courtesy of THE CENTER FOR ECOLITERACY Lower Elementary Food is made up of energy and matter that are passed from one organism to another. Upper Elementary A consistent influx of energy is required for organisms to sustain themselves. Middle School Human activities can affect the balance of food webs on which we vitally depend. Where do living organisms get their food energy? What is a food web and what are the different jobs in a food web? In what ways do people depend on food webs to survive? How do the decisions we make about food affect the natural systems, including food webs? Some source of ‘energy’ is needed for all organisms to stay alive and grow. How do plants use energy from light to make sugar? What happens to the energy when food is transferred from one organism to another? In what ways to people depend on this flow of energy? How do geographical factors, such as climate, location of water resources, and mountains, affect the availability of food energy? In what ways do human activities both depend on and affect food webs? What does knowledge about the flow of matter and energy through living systems suggest for human beings? Food provides molecules that serve as fuel and building materials for all organisms. Plants us the energy from light to make sugars from carbon dioxide and water. Organisms that eat plants break down the plant structures to produce the materials and energy they need to survive. Then they are consumed by other organisms. All organisms, including the human species, are part of and depend on two main interconnected global food webs. One includes microscopic ocean plants, the animals that feed on them, and finally the animals that feed on those animals. The other web includes land plants, the animals that feed on them and so forth. Almost all food energy comes originally from sunlight. Over a long time, matter is transferred from one organism to another repeatedly and between organisms and their physical environment. as in all material systems, the total amount of matter remains constant, even though its form and location change. Environment Almost all kinds of animals’ food can be traced back to plants. One of the most general distinctions among organisms is between plants, which use sunlight to make their food, and animals, which consume energy-rich food. Over the whole Earth, organisms are growing, dying, and decaying and new organisms are being produced by the old ones. Food chains and webs are ways to represent feeding relationships among organisms. The amount of life any environment can support is limited by the available energy, water, oxygen, and minerals, and by the ability of ecosystems to recycle the residue of dead organic materials. Human activities and technology can change the flow and reduce the fertility of the land. The chemical elements that make up the molecules of living things pass through food webs and are combined and recombined in different ways. At each link in the food web, some energy is stored in newly made structures, but much is dissipated into the environment as heat. Continual input of energy from sunlight keeps the process going. At times, environmental conditions are such that plants and marine organisms grow faster than decomposers can recycle them back to the environment. Layers of energyrich organic material have been gradually turned into great coal beds and oil pools by the pressure of the overlying earth. By burning fossil fuels, people are passing most of the stored energy back into the environment as heat and releasing large amounts of carbon dioxide. 101