Strategies
Prior to this unit, my students will have learned the parts of a plant, the parts of a flower, and their functions. They will understand the processes of photosynthesis and reproduction. Next, we will look at the role microbes play in the environment of a plant. I deliberately incorporated numerous science objectives into this unit on microbes to maximize my instructional time. The content areas of science and social studies continue to be limited due to the emphasis on the tested curriculum in math and language arts. In order to combat this problem, and to provide meaningful, rich learning experiences, I intertwined the objectives. It also makes sense because these very same science objectives are intertwined in the real world and do not occur in isolation.
Throughout this curriculum unit, the students will perform hands-on, inquiry-based, and small group collaboration as the strategies for learning. These three strategies are engaging for my fourth graders. These strategies also help to differentiate the instruction so all students can access the curriculum.
We will begin with the roots and the soil. The interactions between organisms that take place in the soil are not only important, but also mostly invisible to the human eye. As a pre- and post-assessment, I want my students to describe what lives in and makes up the soil. I anticipate that most students will only think about the living organisms and organic matter. My students study soil in third grade, so this activity will also give me an informal assessment of their prior knowledge.
Then I will explain that the soil is teeming with life…with millions of microbes. Microbes include bacteria, fungi, protozoa, and viruses. I will provide pictures of microbes for my students to classify and sort. I anticipate that the students will naturally ask questions about the images. As they sort the pictures, they will write down some of their most pressing questions. I imagine the shapes, the body structures and the way the microbes move and eat will be of interest to my students. I want the pictures to draw my students in and to get them interested in the world that resides in the soil.
Next, students will watch a Brainpop video on bacteria and also some clips of videos to answer some of the questions that were generated. We will talk about the different shapes and kinds of bacteria: coccus, spirochete, bacillus (rods), staphylococci (grape-like clusters), rod with polar flagella, diplococci, filamentous, streptobacilli, peritrichous (rod with many flagella), streptococci (string of spheres), and vibrio (comma). It might be fun to make pictures of the different bacteria using their fingerprints. The students will learn that bacteria live both inside and outside of plants. Free-living bacteria that live outside of the plant in the soil are called rhizobacteria. Then we will begin to discuss the soil food web, and what is really happening in the dirt beneath their feet.
Once my students have a basic understanding of bacteria, I will employ more inquiry-based instruction to build their knowledge of fungi, protozoa, nematodes and arthropods.
Working in small groups, each group will have fungi, protozoa, nematodes, or arthropods. The students will develop 5-10 questions that they want to investigate. Using a list of student-friendly links, the students will find and record the answers to their questions. Upon completing the fact finding, students will work with a partner to create an identification card including a picture and basic facts. Students will then share their ID cards with a different group.
My students will work in small groups using the ID cards to write "want ads" representing an organism and describing the type of home and food it seeks. These will be shared with the class. Once my students have a working knowledge of the organisms in the soil, the class will begin to construct a soil food web bulletin board. Each student will choose an organism. Given a rubric, each student will find or draw an image of their organism on the computer and write a brief description. All of the organisms will then be assembled into a representation of a food web. Yarn will be used to show the interrelatedness of the organisms. Throughout the unit, students can add information to the bulletin board.
Then the students will go out into our school garden and, working in small groups, we will conduct a census of the species in the soil (See biodiversity activity below.) In order to further develop my students' higher order thinking skills, we could conduct a second census in a different part of the schoolyard. My students will compare the results and draw conclusions. In an effort to incorporate more inquiry-based strategies, the students will formulate questions about the species they unearth. Then they will seek the answers to their questions using the internet.
Tapping into local resources, it would be informative to invite a guest to speak to my class about the soil food web. Another possibility would be to visit the Rice Center, which is part of Virginia Commonwealth University. The Rice Center is a living laboratory set on 494 acres along the James River. The center provides research and education opportunities and focuses on environmental education.
My students will work in the garden and manage the compost bin throughout the duration of this unit. We will start some vegetable seeds indoors, and then plant them outside in the early spring. Through the work in the garden, my students will encounter many organisms in the soil, and will develop a better understanding of the niches many of the organisms fill.
After learning about the soil food web, I want my students to understand the impact human activity has on the soil food web, particularly applying chemical fertilizers and tilling the soil. Additionally, I want my students to understand some positive alternatives so they can become better stewards of the earth.
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