Lesson Plan: Discovering Plankton

advertisement
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.
Download