Processes Within an Ecosystem

Transcription

1 Grade 6 Science, Quarter 1, Unit 1.1 Processes Within an Ecosystem Overview Number of instructional days: 16 (1 day = 45 minutes) Content to be learned Use data and observations to identify the variety of relationships within an ecosystem including predator/prey, consumer / producer / decomposer, and host/parasite relationship. Use data and observations to predict the outcomes of catastrophic events on ecosystems. Complete a food web for a given ecosystem to trace how matter cycles among and between organisms and the environment. Essential questions How do the various relationships that exist in an ecosystem compare to each other? How are the various relationships that exist in ecosystems impacted by catastrophic events? Science processes to be integrated Use data and observations to predict outcomes. Identify relationships in a system. Make comparisons. Trace the cycle of matter in a system. Create and use models/diagrams. Recognize cause-and-effect relationships. Why are food webs a good way to show the cycling of matter in ecosystems? Why are decomposers important to ecosystems? 1

2 Grade 6 Science, Quarter 1, Unit 1.1 Processes Within an Ecosystem (16 days) Written Curriculum Grade-Span Expectations LS2 - Matter cycles and energy flows through an ecosystem. LS2 (5-8) INQ+SAE -5 Using data and observations, predict outcomes when abiotic/biotic factors are changed in an ecosystem. LS2 (5-6) 5 Students demonstrate an understanding of equilibrium in an ecosystem by 5a identifying and defining an ecosystem and the variety of relationships within it (e.g., predator/prey, consumer/ producer/decomposer, host/parasite, catastrophic events). LS2 (5-8) SAE-7 Given an ecosystem, trace how matter cycles among and between organisms and the physical environment (includes water, oxygen, food web, decomposition, recycling but not carbon cycle or nitrogen cycle). LS2 (5-6)-7 Students demonstrate an understanding of recycling in an ecosystem by 7b completing a basic food web for a given ecosystem. Clarifying the Standards Prior Learning In grades K 2, students cared for plants and/or animals through identification and providing for their needs. Students experimented with a plant s growth under different conditions, such as light or no light. In grades 3 4, students identified the sources of energy involved in an organism s survival. They also acted out or constructed simple diagrams of a simple food web demonstrating that all food begins with the sun. Students have previously explained the way that plants and animals depend on each other. Just as students have used the scientific process skills to learn the content in grades K 4, sixth-graders will use the different process skills to demonstrate content learned. In grade 5, students demonstrated an understanding of recycling in an ecosystem by explaining the processes of precipitation, evaporation, and condensation as parts of the water cycle. 2

3 Grade 6 Science, Quarter 1, Unit 1.1 Processes Within an Ecosystem (16 days) Current Learning The instructional level falls between developmental and reinforcement. While students have exposure to the basic idea of energy in an ecosystem, they are unfamiliar with some terminology that is introduced in grade 5 and 6. Demonstrating an understanding of equilibrium in an ecosystem is a new concept for students in 6th grade. The terms consumer, producer, and decomposer are new to sixth grade and instruction will need to be at the developmental level. Students identify and define an ecosystem as well as the various relationships (predator/prey, consumer/producer/decomposer, and host/parasite). Students should be able to make predictions about how catastrophic events impact an ecosystem. While identifying the sun as a major energy source should be reviewed, students will now be trace the flow of matter in an ecosystem. Given an ecosystem, students will use food webs to trace how matter cycles among and between organisms and the physical environment. They use models or diagram a scenario where they trace the flow of matter through an ecosystem. Students show that organic matter generated by producers directly or indirectly sustains consumer organisms that cannot make their own food. Students show that consumers use, rearrange, and ultimately decompose the materials built up by the producers. Students identify relationships within an ecosystem. Since the movement of organic matter and energy from the producer level through various consumer levels makes up a food chain and interlocking food chains make up a food web, tracing of the cycling of matter can be used as a way to approach this learning. Students can show producer/consumer/decomposer and predator/prey, relationships by identify the feeding patterns in a food web. For example, a typical food chain in a grassland might be: grass (producer) mouse (primary consumer) snake (secondary consumer) hawk (tertiary consumer). By following the overlap between the food chains of the ecosystem (food webs) students can show that the final link in all food chains is made up of decomposers, those heterotrophs that break down dead organisms and organic wastes. By understanding that this matter then returns to the food web, students can show the cycling of matter. Using data and observations, students will predict outcomes when abiotic/biotic factors are changed in an ecosystem. Through inquiry activities, students collect data and observe an ecosystem within the classroom (bottle biology) or in the field (school yard or near by park). Students can use the prior observations to identify various relationships (i.e., predator / prey, consumer / producer, etc.) within the ecosystems. Students will compare the similarities and differences between an aquatic and a terrestrial ecosystem through research, pictures, and first-hand observation. They can observe and draw the cycle of matter through these systems. Students recognize how substances within an ecosystem change when affected by catastrophic events such as pollution, deforestation, or geological processes through the use of bottle biology experiments or research. Students will create a model using pictures that can be manipulated to demonstrate understanding of a food web. As an introduction, students should have an opportunity to identify and define an ecosystem and the variety of relationships within it. Students build a model ecosystem that they can use to identify and define its traits. The focus should be on what students are doing in this grade level and how it is different from what they have done before. 3

4 Grade 6 Science, Quarter 1, Unit 1.1 Processes Within an Ecosystem (16 days) Future Learning In grade 7 and 8, students will identify and analyze how abiotic and biotic factors affect an ecosystem, predicting changes using a visual model. Students will diagram or sequence a series of steps that show how matter cycles among and between organisms and the physical environment. They will develop a model for a food web using local aquatic and local terrestrial environments. In addition, students will explain the inverse nature or complementary aspects of photosynthesis/respiration in relation to carbon dioxide, water, and oxygen exchange. Also, students will conduct a controlled investigation that shows that the total amount of matter remains constant, even though its form and location change as matter is transferred among and between organisms and the physical environment. Additional Findings Like other units, students will have to master the content-specific vocabulary used in this unit, including ecosystem, abiotic and biotic factors, predator-prey, etc. By using real-world models and experiential activities, students will grasp the vocabulary more effectively. (Making Sense of Secondary Science, 59). Some foundational information that students need to be taught to understand in this unit includes the idea of living vs. nonliving things. Students need to identify what is alive and why it is so. (Making Sense, 21). Likewise, students confuse energy as food within an ecosystem, and how the cycle continues constantly for living organisms. Using arrow notation to help students learn a food web has not benefited students as much as using lines to show trophic relationships (Making Sense, 61). Students need real-world models to understand how words like plant and animal can be interchanged with producer, consumer, predator, prey, etc. Students often only see the benefit that the eater or consumer derives in a system, rather than understanding how the entire habitat and/or ecosystem benefit from all the organisms and processes associated from those organisms within it. Lastly, students also have trouble understanding how populations of organisms compete for scarce resources, and how pollution can affect even the most minute and microscopic members of an ecosystem, which in turn, can affect larger members of the system. (Making Sense, 66 69). 4

5 Grade 6 Science, Quarter 1, Unit 1.1 Processes Within an Ecosystem (16 days) Books Notes About Resources and Materials Scott Foresman Reading Street Series Leveled Readers: Ecosystems of the Rain Forests The Battle Over the Rain Forests Tribes of the Amazon Rain Forests Science Explorer: Environmental Science. Upper Saddle River, NJ: Prentice Hall. Chapter 1, Living Things in the Environment, pp ; Interactions Among Living Things, pp Chapter 2, Energy Flow in Ecosystems, pp Science Explorer: Cells and Heredity. Upper Saddle River, NJ: Prentice Hall. Photosynthesis pp ; Respiration pp Book Lists Online Cells Ecosystems Food Webs

6 Grade 6 Science, Quarter 1, Unit 1.1 Processes Within an Ecosystem (16 days) 6

7 Grade 6 Science, Quarter 1, Unit 1.2 Processes Within an Ecosystem Energy Flow Overview Number of instructional days: 5 (1 day = 45 minutes) Content to be learned Trace the flow of energy through an ecosystem, beginning with the sun, through organisms in the food web, and into the environment. Describe the basic processes of photosynthesis and respiration to demonstrate an understanding of energy flow in ecosystems. Recognize the substances involved in photosynthesis and respiration. Essential questions What is photosynthesis and respiration and how are they related to the flow of energy through ecosystems? How do the basic processes or photosynthesis and respiration make it possible for the sun s energy to flow through ecosystems? Science processes to be integrated Recognize processes within a system. Examine energy flow in systems What substances are involved in the processes of photosynthesis and respiration and why can they be used as evidence of recycling of matter and energy in an ecosystem? 7

8 Grade 6 Science, Quarter 1, Unit 1.2 Processes Within an Ecosystem Energy Flow (5 days) Written Curriculum Grade-Span Expectations LS2 - Matter cycles and energy flows through an ecosystem. LS2 (5-8) SAE 6 Given a scenario trace the flow of energy through an ecosystem, beginning with the sun, through organisms in the food web, and into the environment (includes photosynthesis and respiration). LS2 (5-6) 6 Students demonstrate an understanding of energy flow in an ecosystem by 6b describing the basic processes and recognizing the substances involved in photosynthesis and respiration. Clarifying the Standards Prior Learning In grades K 2, students learned that the sun is a source of heat energy and described how the sun warms the land and water. They also learned, by observation, that plants need water, air, food, and light to grow. They observed that animals need water, air, food, and shelter to grow. They learned by caring for plants and/or animals, identifying and providing for their needs and experimenting with plant growth under different conditions including light and no light. In grades 3 4, students cited evidence to distinguish between living and nonliving things. They observed that plants need water, air, food, light, and space to grow and reproduce and that animals need water, air, food, and shelter/space to grow and reproduce. Students identified sources of energy in an ecosystem, such as light and food. They also demonstrated that the food web begins with the sun s energy and designed and built a habitat that supports the organisms within it. They explained the interdependence of plants and animals within that ecosystem as well as the impact of changes or imbalances (caused by fire, human encroachment, weather conditions). They explained various ways the balance of an ecosystem can be disturbed (i.e., overpopulation). Current Learning The developmental instructional level is appropriate for this unit of study. Students have learned that the sun is the major source of energy in a food web but have not learned how energy flows through ecosystems as a result of photosynthesis and respiration. An understanding of photosynthesis and respiration is a new concept for students in the sixth grade. In this unit of study, students will learn the basic processes of photosynthesis, and respiration. It is important that students understand that carbon dioxide and water undergo a chemical change as result of photosynthesis. The result of this change is the production of glucose and the release of oxygen. During respiration, the products of photosynthesis (glucose and oxygen) undergo a chemical change and carbon dioxide and water are the products of this change. The focus of this unit is the flow of energy through ecosystems rather than the chemical processes involved in photosynthesis and respiration. Students should describe how plants use energy from the sun (radiant energy) as they take in carbon dioxide and 8

9 Grade 6 Science, Quarter 1, Unit 1.2 Processes Within an Ecosystem Energy Flow (5 days) water and change them to produce glucose and release oxygen. Consumer organisms eat the substances that are produced as a result of photosynthesis (chemical energy of food). These organisms then change the products of photosynthesis (glucose and oxygen) back into carbon dioxide and water. This process (respiration) is the step that makes the energy stored in food available to other organisms in an ecosystem. Students can demonstrate their understanding of the flow of matter and energy through these coupled processes by producing flow charts or diagrams that require them to indicate the flow of energy as it flows from it source (the sun) through the organisms in a food web. Future Learning In grades 7 8, students will explain the transfer of the sun s energy through living systems and its effect upon them. Students will explain the relationship between photosynthesis and respiration. They will also recognize the names and chemical formulas of substances involved in photosynthesis and respiration, while tracing the flow of energy in a food web. In high school, students will diagram the energy flow in an ecosystem to compare the energy at different trophic levels. Students will also explain how the chemical elements and compounds that make up living things pass through food webs and are combined and recombined in different ways. Students will also explain the energy transfer with cells in photosynthesis and cellular respiration, tracking ATP production and consumption. Additional Findings One of the greatest challenges to middle school students who first encounter this unit of study is grappling and using the vocabulary involved with the photosynthesis process. Specifically, respiration is a difficult concept for them to understand unless they have real-world processes and experiences to demonstrate it (National Science Education Standards pp ). Photosynthesis is often seen, not as something important to plants themselves, but as something that plants do for the benefit of people and animals, particularly in relation to exchange of gases (Making Sense of Secondary Science p. 33). Students need to understand that energy flows in one direction and can also be called food for some organisms. Students often do not understand energy as food. Because of this confusion and their misconception of food, students may be unable to understand how energy converts within the process to create different by products. Students do not understand that photosynthesis is a constant and cyclical process (Making Sense of Secondary Science pp ). The integration of ideas about feeding and energy into an ecological perspective is not evident in the thinking of many students. Only half of a sample of undergraduate biology students, when asked about the phrases life depends on green plants and the web of life, explained in terms of food chains. Only a minority of these mentioned harnessing solar energy or photosynthesis as the reason why green plants are crucial in the food chain. Even at the tertiary stage of education, nearly a quarter of the students expressed views suggesting that other organisms exist for the benefit of humans. A subsequent study of students, from age 13 up to undergraduate level, revealed that most students knew that animals could not exist in a plant-free world, but some thought that carnivores could exist if the prey reproduced plentifully. About half of the students at each age level indicated that animals could not live without plants because of their oxygen need, but only about 10 percent mentioned the oxygen cycle in the context of the sun s part in the origin of life. (Making Sense of Secondary Science pp ). 9

10 Grade 6 Science, Quarter 1, Unit 1.2 Processes Within an Ecosystem Energy Flow (5 days) The best strategy to teaching photosynthesis is to use real-world diagrams, videos, experiments, field study, etc., to improve their understanding of this dense vocabulary (Making Sense of Secondary Science, pp ). 10

11 Grade 6 Science, Quarter 1, Unit 1.3 Characteristics of Living Organisms Overview Number of instructional days: 10 (1 day = 45 minutes) Content to be learned Define reproduction as a process through which organisms produce offspring. Describe reproduction in terms of being essential for the continuation of a species. Illustrate the structural organization of an organism from a cell to tissue to organs to organ systems to organisms. Explain relationships between or among the structure and function of the cells, tissues, organs, and organ systems in an organism. Essential questions Why is reproduction essential to the survival of a species? Science processes to be integrated Describe and explain patterns of change. Explain the relationship between structure and function. Use flow charts to illustrate scientific processes. What are the relationships between or among the structure and function of the cells, tissues, organs, and organ systems in an organism? 11

12 Grade 6 Science, Quarter 1, Unit 1.3 Characteristics of Living Organisms (10 days) Written Curriculum Grade-Span Expectations LS1 - All living organisms have identifiable structures and characteristics that allow for survival (organisms, populations, & species). LS1 (5-8) POC -3 Compare and contrast sexual reproduction with asexual reproduction. LS1 (5-6) 3 Students demonstrate an understanding of reproduction by 3a defining reproduction as a process through which organisms produce offspring. 3b describing reproduction in terms of being essential for the continuation of a species. LS1 (5-8) FAF 4 Explain relationships between or among the structure and function of the cells, tissues, organs, and organ systems in an organism. LS1 (5-6) 4 Students demonstrate understanding of differentiation by 4b recognizing and illustrating (e.g. flow chart) the structural organization of an organism from a cell to tissue to organs to organ systems to organisms. Clarifying the Standards Prior Learning In grades K 2, students demonstrated understanding of an ecosystem by caring for plants and providing for their needs. Grade 1 students sequenced life cycles of plants and animals when given pictures of these organisms; however, the reproductive process was not presented. In grades 3 4, students demonstrated understanding of reproduction by sequencing the life cycles of plants and animals and comparing the life cycles of two organisms. Students also demonstrated understanding of human body systems by comparing and analyzing external features and characteristics of humans and animals. In grade 5, students investigated and compared a variety of plant and animal life cycles. Students also identified cells as the building blocks of organisms and defined reproduction as a process in which organisms produce offspring. Students were introduced to the idea that reproduction is essential to the continuation of a species. 12

13 Grade 6 Science, Quarter 1, Unit 1.3 Characteristics of Living Organisms (10 days) Current Learning The developmental level of instruction is appropriate for this unit of study. Students have some prior knowledge about the structures that help organisms survive but have not focused on reproduction as a process. In this unit of study, students will learn about reproduction as it applies to structure and function. It is important to emphasize how the process differs in plants and animals. This does not include teaching the specifics of human reproduction; instead, students should discuss the basic processes involved in beginning and continuing a species. Students describe reproduction as an essential continuation of the species. Students will learn how the different levels of organization in complex organisms allow for survival. They begin by learning that cells are the building blocks of organisms. They learn that there are many different types of cells and that each cell serves a function. This understanding of cells is applied to the next level of organization tissues. Students learn that there are many different types of tissues and that these tissues are made up of different types of cells, depending on the function of the tissue. Students then learn that the next level of organization is the organ, which is made up of different tissues and the tissues are made up of different cells, all of which support the survival of the organism. Students apply the same reasoning to their study of organ systems and finally the entire organism. Students make use of models and diagrams to show the organization of an organism from cell to tissue, to organ, to organ system, and to organism. This could be a flow chart or drawings. Students need to be able to explain the relationship between the structure and function at each of these levels. For example, students should understand that nerve cells have a specific structure that makes it possible for them to transmit messages, throughout the body; bone cells have a specific structure that makes it possible for them to form bones, etc. Students should also apply this same understanding to different tissues, organs, and organ systems. Future Learning In grade 7, students will explain how cells have the same survival needs as organisms. They will observe and describe individual cells as seen through a microscope, targeting the cell membrane, cell wall, nucleus, and chloroplast. Students will observe, describe, and chart the growth, motion, and response of living organisms. In eighth grade, students will explain reproduction as a fundamental process by which a new individual receives genetic information from parent(s). Students should be able to describe forms of asexual reproduction that involve the genetic contribution of only one parent (for example, budding, vegetative propagation, etc.) and describe sexual reproduction as a process that combines the genetic material of two parents to produce a new organism (for example, sperm/egg, pollen/ova). Eighth-graders will explain that specialized cells perform specialized functions. They will also compare individual cells of tissues and recognize the similarities between cells and how they function together to perform specialized functions. Students will explain how each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole. Additional Findings Within cells, many of the basic functions of organisms such as extracting energy from food and getting rid of waste are carried out, and the way in which cells function is similar in all organisms. (Benchmarks for Science Literacy, p. 112) 13

14 Grade 6 Science, Quarter 1, Unit 1.3 Characteristics of Living Organisms (10 days) In the middle-school years, students should progress from studying life science from the point of view of individual organisms to recognizing patterns in ecosystems and developing understanding about cellular dimensions of living systems. Middle school students also begin to develop the understanding that the body has organs that function together to maintain life. Living systems at all levels of organization demonstrate the complementary nature of structure and function, which includes cells, organs, tissues, organ systems, whole organisms, and ecosystems. Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole. In addition, behavior is one kind of response an organism can make to an internal or environmental stimulus. A behavioral response requires coordination and communication at many levels, including cells, organ systems, and whole organisms. (National Science Education Standards, pp ) Middle school students can extend their previous knowledge that some organisms are made up of cooperating cells to comprehend that different organs are made up of different kinds of cells and organs that serve the various needs of all cells, and that communication between cells in the same or different organs is essential to the living system. (Atlas for Science Literacy, p. 74) Some students seem to confuse the concepts of cell and molecule. In addition, students have similar confusion about the order and magnitude of levels of organization. (Making Sense of Secondary Science, p. 25) Preliminary research indicates that it may be easier for students to understand that the cell is the basic unit of structure (which they can observe) than that the cell is the basic unit of function (which has to be inferred from experiments). Research also shows that high-school students may hold various misconceptions about cells after traditional instruction. (Strand map 14

15 Grade 6 Science, Quarter 1, Unit 1.3 Characteristics of Living Organisms (10 days) Books Notes About Resources and Materials Science Explorer: Human Biology and Health. Upper Saddle River, NJ: Prentice Hall. Levels of Organization of the Body, pp Science Explorer: Bacteria to Plants. Upper Saddle River, NJ: Prentice Hall. Chapter 1, What is Life? pp ; Chapter 4, The Plant Kingdom, pp Science Explorer: Environmental Science. Upper Saddle River, NJ: Prentice Hall. Chapter 1, Living Things in the Environment, pp ; Interactions Among Living Things, pp Chapter 2, Energy Flow in Ecosystems, pp Science Explorer: Animals. Upper Saddle River, NJ: Prentice Hall. How Cells are Organized, p. 17; Asexual Reproduction, p. 18 Sexual Reproduction Plant Parents Lesson Plant Propagation Asexual Reproduction

16 Grade 6 Science, Quarter 1, Unit 1.3 Characteristics of Living Organisms (10 days) 16