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        3-5

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        Living Life as a Plant

        In this media-rich lesson, students investigate how plants respond to their environment. They also explore adaptations, such as how some plants are adapted to life in the desert and why some plants trap and digest insects.

        Lesson Summary

        Overview

        In this lesson, students explore how plants are well adapted to their surroundings. First, a class discussion brings out that plants need a source of chemical energy, substances to build plant material, and water to survive. Students watch a series of short time-lapse videos in which they see how plants respond to their environment. Next, they view a video about plants living in the desert and identify ways in which plants are adapted to their surroundings. Finally, students extend their understanding by considering why some plants have evolved to get nutrients and energy from insects.

        Objectives

        • Give examples of plants sensing and responding to their surroundings
        • Describe the challenge plants face living in the desert
        • Give examples of how plants have adapted to life in the desert
        • Explain why some plants trap and digest insects

        Grade Level: 3–5

        Suggested Time

        • Four 45-minute class periods

        Multimedia Resources

        • Plants-in-Motion Flash Interactive
        • Desert Biome QuickTime Video
          [Note: This video begins with descriptions of how plants are adapted to an arid environment. The rest of the video concentrates on animal adaptations. For the purpose of this lesson, students will only need to watch the first third of the video that focuses on plants.]
        • Carnivorous Plants QuickTime Video
          [Note: The text that accompanies this video provides you with some useful background information. However, it is written at a level that is too high for students in grades 3–5. Instruct students to ignore the text and just focus on the images of the seeds and plants.]

        Materials

        • For each group of two students you will need:
          • Four pre-soaked corn seeds
          • Petri dish
          • Paper towels

        Before the Lesson

        • If possible, arrange computer access so all students can work in pairs.
        • Prepare overhead transparencies and copies of all PDFs.
        • Gather all materials for seed germination activity.

        The Lesson

        Part I: Obtaining Nutrients

        1. Display the Plant Type Comparison PDF Document showing different types of green plants. Ask students, "What is food for? Why do plants and animals need it? How do animals get food? How do plants get food?"

        Guide the discussion to bring out that food serves two main functions. First, it provides the energy needed by the organism to survive. Second, it provides the chemical building blocks that the organism requires to make needed structures. Animals get food by eating plants or other animals. Plants can make their own food. Their green leaves absorb sunlight and use this energy to make sugars which they use as food.

        2. Ask students what they think is meant by "food" when we talk about plants. Some students may be aware that green plants can use sunlight as an energy source. Although it is not important for students to be familiar with photosynthesis, be sure to explain that green plants are special in that they can make their own food from the Sun's energy and from carbon dioxide in the air.

        3. Next, ask students, "How do these plants get food and water?" Refer back to the previous step and make the connection between green leaves and food production. Students will recall that plants take in water through their roots. Guide the discussion to bring out that the water in the soil also contains minerals that plants need for their health. Explain that certain minerals in the soil are needed because they provide the plants with building blocks to make their body parts.

        4. Remind students that plants don’t have brains or senses such as sight, hearing, and smell. Then ask them the following questions:

        1. Do you think that a germinating seed can tell which direction points toward the Sun?
        2. Do you think that a germinating seed can tell which direction is down so that its roots may contact water?
        3. Do you think that plants move? Explain your answer.

        At this time, accept all answers. Explain that they will explore these questions by viewing a series of short videos and performing their own experiment.

        5. Divide students into pairs and provide them with the materials needed to germinate soaked corn seeds. Explain that they are going to perform an experiment to see if germinating corn seeds can tell up from down. Demonstrate the experimental setup as follows:

        1. Place four pre-soaked corn seeds into a Petri dish on top of moistened paper towels so that the narrow end of each seed points toward the center of the dish. Turn the Petri dish on its side.
        2. Observe the seeds for several days.
        3. Be sure that there are enough paper towels in the dish to keep the seeds in position and so they do not fall to the bottom of the dish.

        6. (Optional) While students are making daily observations of their corn seeds, you may also want to have them watch how a leafy plant responds to light at the same time. If possible, put a leafy potted plant near a bright window and have students predict and observe what the leaves will look like after a day or two in that position.

        Part II: Responding to Surroundings

        7. Explain to students that they will watch several short videos of seeds sprouting and plants growing. Further explain that in these videos, hours or days of plant growth are shown in just a few seconds. Have students view Video 1 in the Plants-in-Motion Flash Interactive to see germinating corn seeds. Show the video twice: the first time so that students get a general idea of how it happens, and a second time so that they can observe the patterns of growth. Ask them what they learned from the video about how corn seeds sprout. Guide the discussion to bring out the following:

        • Roots grow downward toward the soil.
        • Shoots grow upward toward the air.
        • It doesn't matter if the seed is "upside down," the roots and shoots still grow in the right direction.
        • Be careful to stress that the roots don't grow purposefully downward searching for water.

        If students' corn seeds have germinated, have them compare their seeds to those shown in the video.

        8. Next, ask students if they think that seeds whose roots grow downward would have an advantage over seeds whose roots did not. Guide the discussion to bring out that the seeds whose roots grow downward are more likely to contact water and promote the survival of the plant.

        9. Ask students what they think will happen if a plant growing in a pot is turned on its side. Try to focus students' responses on the direction in which the leaves and stem will grow. You may want to ask students to draw how they think the plant will grow when placed on its side.

        Then have students view Video 4 in the Plants-in-Motion Flash Interactive and see if the plant response supports or refutes their predictions. Students should see that plants can respond to gravity so that shoots and leaves move (grow) and reorient upward toward the sky while the roots move (grow) downward into the soil.

        10. Next, have students think about light. Remind students that plants don’t have eyes. Ask, "Do you think that plants can sense light?" Explain that in the next video they will see sunflower seeds sprouting in the darkness and in the light. Instruct students to look for differences in growth between the seeds kept in the dark and in the light.

        Now show students Video 2 of the Plants-in-Motion Flash Interactive. Ask them to describe the differences they saw between the seeds sprouting in the dark and the light. Perhaps the most notable difference that they may mention is that the shoots grow taller in the dark as compared to the light. Ask students why they think this happens. Ask them what they think the absence of light might have to do with this.

        11. Tell students that they will now see a video of an oxalis (lucky shamrock) plant growing in a room where a light is turned on for half of the day. Ask students to predict how the leaves will respond to the light and to the dark.

        Then have students view Video 5 of the Plants-in-Motion Flash Interactive and see if their predictions were supported by the video. Students should see that the leaves lift toward the light and close when they are in the dark.

        12. Conclude this part of the lesson by revisiting the questions posed at the end of Part I. Instruct students to use evidence from their experiment or the videos to support their answers.

        1. Do you think that a germinating seed can tell which direction points toward the Sun?
        2. Do you think that a germinating seed can tell which direction is down so that its roots may contact water?
        3. Do you think that plants move? Explain your answer.

        Guide the discussion to bring out that although plants don't have the brains or senses that we posses, they still respond to their surroundings in ways that are important for their growth and health.

        Part III: Fitting In

        13. Explain to students that they are about to watch a video that describes plants living in the desert. Ask them, "What do you think is the biggest problem for plants that live in the desert?" Students' answers will vary, but focus the discussion on the need to obtain and conserve water.

        14. Divide the class into pairs and give each pair a copy of the Plants Living in the Desert PDF Document. Have students watch the first part of the Desert Biome QuickTime Video that describes how plants are adapted to the desert environment. [Note: Students do not need to watch the rest of the video, which focuses on animal adaptations.] Instruct the groups to identify at least four characteristics of plants in the desert that help them to survive in the harsh climate.

        15. After the groups have completed their task, ask for volunteers from each group to share their results. Write their answers on the board or on an overhead transparency.

        Part IV: Applying Knowledge

        16. Ask students why they think the adaptations used by desert plants wouldn't work as well for plants living in other environments, such as a rain forest. Lead the discussion to the idea that, just as the plants living in the desert are well suited to live in that environment, plants living in other types of places are well suited to those environments.

        17. Have students stay in their pairs and pass out to each group a copy of the Plants That Trap and Digest Insects PDF Document. Have students view the Carnivorous Plants QuickTime Video. Instruct them to answer the questions on the handout.

        18. After students have answered the questions on the handout, ask for volunteers to read their responses aloud. As before, write their answers on the board or on an overhead transparency.

        Check for Understanding

        1. Pass out to each student a copy of the Living Life as a Plant PDF Document. As students answer the questions on the handout, instruct them to reflect on what they have learned from germinating seeds, watching the videos, and the classroom discussion.
        2. As students finish their document, display a transparency of the handout. Ask for volunteers to share their answers to each question. After each response, ask if the rest of the class agrees. If there are disagreements, have students provide evidence for their answers.

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