Lesson Plan: Discovering Plankton Written by: Douglas Weittenhiller II [email protected] Introduction What follows is a series of activities to engage your students about simple aquatic life and teach basic anatomy and ecology. You will be using lake or ocean water that looks clear but is really a part of a much larger ecosystem. The activities follow a Learning Cycle instruction method (Karplus 1977) and can be easily adapted to your middle school or junior high classroom. Background Prior Knowledge These activities assume students… … have seen lakes and oceans before. … understand that water has small aquatic life (plant and animal). … know that plant life undergoes the process of photosynthesis. Rationale for Content These activities show students how … … the aquatic ecosystem affects both aquatic and terrestrial life. … small organisms often form the first link in a food chain. … plants always form the basis for a food chain. … plants and animals rely on each other. Rationale for Methods Students will be … … identifying what plankton looks. … observing the movement of plankton under the microscope. … discussing their observations with classmates. … receiving first-hand experience with the content they are going to be studying. … semantic mapping so as to express what they already know about ocean life. Specific Scientific Concepts Introduced Similarities/Differences between Zooplankton and Phytoplankton. Similarities/Differences between producers and consumers. Plankton in the (ocean’s) food chain. Objectives The students will draw basic aquatic food chains. The students will identify phytoplankton and zooplankton through the microscope. The students will label plankton as either a producer or a consumer. Time Estimate: 2-3 days Grade Level: 6-9 Materials Water Sample If possible, purchase a freshwater or saltwater sample that will have increased diversity . Fisher Scientific Catalog #S244867 . VWR Catalog #WL3911A-19 . Carolina Biological Supply Company #WW-13-2050 If not possible, obtain and maintain a sample from a local body of water Stereo Dissecting Microscope Objective Microscope Glass Slides Slide Covers Petri Dish Eye Dropper Immersion Oil (optional) Alcohol (70% EtOH for cleaning the slides) Plankton Identification Chart http://www.bigelow.org/flowcam/chart1.gif (included in references) http://www.bigelow.org/flowcam/chart2.gif (included in references) Pictures of Animals in a Food Chain http://www.britishecologicalsociety.org/articles/education/resources/curriculum/foodchains/cards/ Large piece of construction paper or a large presentation board Tape (or something to adhere animal pictures to construction paper/presentation board) Procedure Beginning – The Concept Exploration Plankton Microscope Activity: The activities begin with the first part of the Learning Cycle. The instructional goal is to begin with an activity that introduces the topic in an exciting way while keeping the classroom student-centric. Dr. Arthur W. Combs once said, “Things which have no personal meaning arouse no emotions.” Since students love gross and discrepant events, show them a bottle of water (the sample containing the plankton) and ask if anyone would drink it. Determine if they believe anything is in the bottle. The teacher can have some fun with the responses, but the point is to generate interest. (Note: Do NOT let a student drink the water containing the plankton sample!) The students will work in pairs and look at the water sample under the microscope. A stereo microscope is suggested to begin with to see if larger plankton are present. Also view samples under an objective microscope at 100X and 400X. Provide the students with the included Identification Chart and have them draw what they see. (They can either check off which plankton they see or draw what they observe.) Do not formally introduce concepts and vocabulary yet (next activity). Teacher Role: The teacher does not begin with a lecture. Rather, the activity commences right away with students receiving their water samples and recording what they see. The teacher observes and questions the students’ discoveries. Student Role: The students will be activity engaged in looking at the “stuff swimming in the water.” They will be challenged to use the microscope to focus on and observe plankton as well as to draw what they see onto paper. They will consult with their partner on what they see. Time: Briefly introduce the activity: No more than 5 minutes Setup partners and microscopes: No more than 10 minutes Perform the activity: 20-35 minutes Cleanup: 5 minutes —————————————————————————–––––– Total Time: 35 minutes to 1 full class period [Optional Assessment: If microscope handling and care has been recently taught, assess the students’ performance while operating and transporting the microscopes.] Questions to Ask What do you see? What is that little “stuff”? Is it moving? Is it alive? How many objects do you see? Why can’t you see them without the microscope? During – Concept Introduction Discussing the Plankton Microscope Activity: Continuing with the learning cycle, the class is brought back together for a more formal teacher-centric discussion. Here, the teacher discusses what the students saw and discuss the students’ data using the students’ terminology. Activate the schemata they already have (or think they have) and build upon that. Since the class was able to see and touch the concept first, they are more receptive to new labels for new words. Thus, now is also the time to introduce new vocabulary. As a suggested technique to learn what the students know, begin with a semantic mapping activity. The teacher picks a central concept and writes it on the board. It is important to pick a concept that they can understand well enough to offer words that will relate to the meaning. For example, use “ocean”. Students will volunteer their words related to the ocean. (This is a great way to introduce the important elements of a food chain!) The teacher will write the students’ words on the board and, with the help of the students, the teacher will group the words into broad categories. Students will then name each category. Finally, the teacher and students will discuss the ocean and the life that takes place within it. You can ask some very fun questions like “what does a plant eat?” or “why are there more plankton than things that feed on plankton?” To complete this activity, introduce the concepts of phytoplankton vs. zooplankton and producers vs. consumers. To do this, return again to the plankton activity and ask the students to guess if the plankton are plants or animals. Introduce those that are plants as phytoplankton and those that are animals as zooplankton. Ask what phytoplankton consumes to make energy and label them as producers using the drawing the students made from the last activity. Also ask what zooplankton consumes to make energy and label those as consumers. Teacher Role: The teacher is more traditional in approach, but still avoids giving students direct facts. The teacher discusses the students’ data and uses their terminology, yet introduces new vocabulary words only after students have introduced the concept. Student Role: The students will be activity engaged sharing and discussing their results. Time: Discuss the students’ results: 10-15 minutes Discuss new vocabulary: 5-10 minutes Concept of phytoplankton/zooplankton: 10-15 minutes Concept of producers/consumers: 5-10 minutes —————————————————————————–––––––––––– Total Time: 20 minutes to 1 full class period Vocabulary with Definitions Consumer: an organism requiring complex organic compounds for food that it obtains by preying on other organisms or by eating particles of organic matter. Food chain: a sequence of organisms that are associated with each other by a simple feeding relationship in nature. In a food chain, each organism eats another species, and in turn, it is eaten by another species in the sequence. Photosynthesis: the manufacture of carbohydrate food from carbon dioxide and water in the presence of chlorophyll, using light energy and releasing oxygen. Phytoplankton: plant plankton. They are the basic synthesizers of organic matter (through photosynthesis) in the ocean. Plankton: the mostly microscopic organisms that are free-floating or drifting in the open water of the oceans having their lateral and vertical movements determined by water motion. Producer: any of various organisms that produce their own organic compounds from simple precursors (carbon dioxide and inorganic nitrogen). Most are the food sources for other organisms (consumers). Zooplankton: animal forms of plankton. They include various crustaceans, such as copepods, jellyfish, certain protozoa, mollusks, and the eggs and larvae of benthic and nektonic animals. Questions to Ask What did you see in that clear water? Would you still drink it? How are the zooplankton/phytoplankton similar? Different? What characteristics of plankton indicate if they are producers? Consumers? Wisconsin DPI Standards STRUCTURE AND FUNCTION IN LIVING THINGS F.8.2 Show *how organisms have adapted structures to match their functions*, providing means of encouraging individual and group survival within specific environments. After – Concept Application “What Eats What” Activity: The final stage of the learning cycle presents the students with a challenging activity that applies the recent knowledge they have gained. The activity is back to being student-centric with the teacher acting as the overseer. The students will be provided with 4-6 pictures of animals from a generic food cycle. In groups of 2-4, students will discuss ‘what eats what’ based on knowledge from the previous activities. The students will affix these pictures to a large presentation board (or construction paper) and draw lines representing their food chain. The students will then present their chains to the class and defend their decisions. They should be using terminology like, “this is the start of the chain because it is a producer”. Optionally (if time permits) after the discussion, give the students another picture to add to their web. Again have the students defend their decisions to the class. Teacher Role: The teacher again is the observer. Resist the temptation to do the work for a struggling student. Rather, given him/her encouragement and hints. Assess the students’ use of the new terminology in this new concept. Student Role: The students will be activity discussing with their partners what causes the food chain to progress. Formal roles (recorder, presenter, etc) need not be given so each student has an equal part. The students will present and defend their arguments to the class, very similar to the way science actually works. Time: Briefly introduce the activity: No more than 5 minutes Setup partners and gather materials: No more than 5 minutes Perform the activity: 10 minutes Discuss and defend: 20 minutes Additional picture (optional): 5 minutes Additional discussion (optional): 10 minutes Cleanup: 5 minutes ————————————————————————— Total Time: Approximately 55 minutes Questions to Ask What do you think would happen if the phytoplankton were unable to carry out photosynthesis? What affect would an alga bloom have on the phytoplankton? On the zooplankton? On animals that feed on plankton? How would this affect other life forms in the ocean and on land? How does photosynthesis carried out by phytoplankton benefit fish, animals and humans? Wisconsin DPI Standards POPULATIONS AND ECOSYSTEMS F.8.8 Show *through investigations* how organisms both depend on and contribute to the balance or imbalance of populations and/or ecosystems, which in turn contribute to the total system* of life on the planet. DIVERSITY AND ADAPTATIONS OF ORGANISMS F.8.9 Explain *how some of the changes* on the earth are contributing to changes in the balance of life and affecting the survival or population growth of certain species. Assessment I know I will have met my objectives when the students correctly identify the plankton organisms under the microscope by comparing them to the provided chart. I know I will have met my objectives when the students can draw a logical food chain and can identify which organisms of the food chain are producers (in water and land) and which organisms (in water and land) are consumers. I know I will have met my objectives when the students can verbally communicate how a basic aquatic ecosystem functions and how life on land benefits. References Karplus, R. (1977). Science Teaching and the Development of Reasoning. Journal of Research in Science Teaching, 14, 169. A special thank you to Bigelow Laboratory for Ocean Sciences (http://www.bigelow.org) for the use of their plankton identification charts. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.