The Drift on Plankton
Chris Lundberg, Mathematics & Science Center
Revised from The World of Phyto- and Zooplankton: Life at Low Reynolds
Number, by Dr. Mark Patterson, Virginia Institute of Marine Science
Major
Understanding
Objectives
Plankton are the minute drifters of rivers, ponds, lakes, estuaries, and oceans.
They also play an important role in aquatic food chains. Because of their small
size in relation to their aquatic environment, both phytoplankton and
zooplankton exhibit a wide variety of physical adaptations that aid in their
survival. In this lesson, students will observe how fluid motion at small scales
is very different from those of experienced by a larger organism and will
perform an experiment to test their own hypotheses concerning the many
physical adaptations of plankton.
Observe and describe the role of phytoplankton and zooplankton in the
aquatic food chain.
Develop a hypothesis concerning plankton shape and conduct an
experiment using a scale physical model to test their hypothesis.
Discover and explain how differences in physical structure affect the
sinking rate of phytoplankton and the evolution of feeding mechanisms
in zooplankton.
Understand and appreciate the impact of size and scale on the forces and
limiting factors affecting aquatic organisms.
Time
Introduction
Activity: Observation of Live Plankton
Activity: Plankton-Sinking Syrup Experiment
Practice and Review of Results
Closure
Materials
Observation of Live Plankton Activity
Zooplankton, phytoplankton samples from biological supply company,
local pond, or hay infusion set-up.
Microscopes and Dissection scopes
10 min
30 min
30 min
10 min
10 min
Plankton-Sinking Syrup Experiment
(For a class of 24: 6 set-ups for groups of 4)
Student Handout: The Drift on Plankton
1 Stopwatch
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1 Meter stick or small metric ruler
Plasticine modeling clay (for 4 similar sizes)
1 liter plastic bottle (with top cut off)
16 toothpicks
2 bottles of corn syrup
1 Coat hanger (to retrieve models from syrup)
Paper towels
Note: See Sources of Lesson Materials below in Teaching Tips for more
information and preparation of lesson materials.
State and National
Correlations
Virginia Standards of Learning: Life Science (LS.1, LS.4, LS.5, LS.7, LS.10);
Physical Science (PS.1, PS.6, PS.10); Biology (BIO.1, BIO.5, BIO.7, BIO.8,
BIO.9, PH.1)
National Council of Teachers of Mathematics: Content Standard A (develop
descriptions, explanations, predictions, and models using evidence, think
critically and logically to make the relationships between evidence and
explanations); Content Standard C (structure and function in living systems,
regulation and behavior, populations and ecosystems, diversity and adaptations
of organisms).
Instructional
Strategies
Introduction
Review with students the definition of plankton and describe how they
experience their water environment much differently than larger organisms.
Teachers may want to review the background information on plankton for this
part. Teachers can use the PowerPoint presentation to introduce the concepts
of types of plankton, reasons for their unique adaptations, and to introduce the
sinking plankton lab activity.
Activity: Lab observation of plankton
Obtain living plankton samples for students to observe. Have students look for
ornamentation, fat globules (which may affect buoyancy) and make drawings
of their observations. Discuss the role of these shapes in regard to defense
from predators and influence on the sinking rate of the organism.
Introduce syrup experiment by stating that they are going to replicate the world
of plankton in a larger, easier to observe setting.
Activity: Sinking Syrup Experiment.
Set up the experiment for students with cylinders, syrup, and materials.
Students should work in groups of 4. Hand out the materials and the
Drift on Plankton Student Handout and model or review the directions below
for the activity:
Have each student prepare a ball of clay of same mass.
Direct students to take turns dropping their ball into the center of the solution
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and recording the time from drop to hitting the bottom.
Have students hypothesize what shapes might help slow down the sinking time
of their balls of clay.
Direct students to use 4 of the toothpicks to modify and change the shape of
their clay ball of “phytoplankton.” Students should make drawings of their
creations on their answer sheet. Have students hypothesize which of their
creations will sink the slowest. Sample hypotheses are: there is no effect of
cell ornamentation on sinking rate, there is no effect of buoyancy changes
(make a hollow ball), there is no effect on size on sinking rate.
Direct students to again take turns dropping their ball into the center of the
solution and recording the time from drop to hitting the bottom. Record which
shape sank the slowest.
Have students repeat the experiment, but this time allow them to drop their
creations by the side of the syrup cylinder wall and record their results.
Practice
As a practice activity for an in-class or homework assignment, instruct students
to perform one of the following two options:
Conduct a web quest to find photographs or diagrams of different kinds of
plankton. Make a drawing or print out a picture of the plankton and describe
how its shape or form helps its floating function. Then, design a possible
experiment a scientist could conduct – with a completed experimental design
diagram – to test how well the plankton can float.
Search for materials and items around the home that are designed to float in
water. Make a list of these items and describe what allows each item to be able
to float. Then, design an experiment – with a completed experimental design
diagram – to test how you would change the buoyancy of one of these items.
Closure
Bring the lesson to closure by reviewing student results and the concept of
surface to volume ratio with students. Ask students to respond to the following
questions to relate their experiment to plankton and other living organisms in
the Chesapeake Bay:
How might sinking rate affect the delivery of food to benthic creatures?
In the bay in the summer, hypoxia in deeper water is a problem for organisms.
Would certain kinds of phytoplankton be less likely to cause an organic matter
accumulation?
How can an increase or decrease in limiting factors such as nutrients or water
temperature affect the amount of plankton in the bay?
Extensions
1. Explore Plankton Physics. Have students research Archimedes’ Principle
and explain how relative density, volume, pressure, buoyancy, weight,
displacement, and gravity relate to the classroom experiment and to the
characteristics of microscopic aquatic organisms.
2. Create a Cartesian Diver. Have students create their own Cartesian Diver.
Go to our Household Science for Kids or Cartesian Diver links for information
and directions to create and conduct your own experiment.
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3. A Copepod Feeding Mechanism Experiment
Students can perform the experiment below to model and understand the
challenges for zooplankton in regard to obtaining food.
Materials
Corn syrup, Small Styrofoam bowl, Nylon stocking, Cake sprinkles,
Popsicle sticks, Toothpicks
Directions
Fill a small bowl with corn syrup to create a “corn syrup aquarium.” As you
fill your aquarium, periodically add the cake sprinkles. Try to get a uniform
suspension of them in the tank.
Direct students to try to sieve the particles out of the tank using a filter made of
pieces of nylon stocking strung between two Popsicle sticks. Make drawings
of what happens.
Brainstorm with students other methods to retrieve the particles. Direct
students to fabricate tools (to replicate a copepod’s mouthparts) to be able to
grab the food particles.
Assessment
Sample items are provided for use in checking students’ understanding of
experimental design and plankton adaptations:
Paper-Pencil Test: The Drift on Plankton
Answer Key to Paper-Pencil Test
Product: Create a Paper Plankter
Rubric: Create a Paper Plankter
The following table shows how the assessment items are related to specific
lesson objectives:
Objective
Observe and describe the role of
phytoplankton and zooplankton in the aquatic
food chain.
Develop a hypothesis concerning plankton
shape and conduct an experiment using a
scale physical model to test their hypothesis.
Discover and explain how differences in
physical structure affect the sinking rate of
phytoplankton and the evolution of feeding
mechanisms in zooplankton.
Understand and appreciate the impact of size
and scale on the forces and limiting factors
affecting aquatic organisms.
Major Understanding: Plankton are the
minute drifters of rivers, ponds, lakes,
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Paper-Pencil
Test
2, 7
Product/
Performance
3, 4, 5, 12, 13,
14
1, 6, 8, 11
9, 10, 15
See attached
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estuaries, and oceans. They also play an
important role in aquatic food chains.
Because of their small size in relation to their
aquatic environment, both phytoplankton and
zooplankton exhibit a wide variety of physical
adaptations that aid in their survival.
Teaching Tips
rubric
Check out these teaching tips for background information, teaching notes, and
sources to obtain materials and living or prepared specimens for this lesson.
Answer Key to Paper-Pencil Test
Background Information
Sources of Lesson Materials
Student Handout: The Drift on Plankton
References
Chesapeake Bay Network
This site provides general information, publications, and data concerning
plankton in the Chesapeake Bay.
http://www.chesapeakebay.net/info/plankton.cfm
MathInScience.info
Visit our educational resource site to acquire web-based lessons and resources
for students and teachers.
http://mathinscience.info
Mathematics & Science Center
Web site of the Mathematics & Science Center with a variety of information
on programs and opportunities for students.
http://mathsciencecenter.info
The Plankton Net
The homepage of all things plankton related and marine biology links by the
Plankton guy, Dr. Warren Currie. Information on plankton ecology, research,
images, and databases. Originally hosted by University of Guelph, Canada.
http://www.geocities.com/planktonguy/index.htm
Virginia Institute of Marine Science
Web site of the Virginia Institute of Marine Science, with information
concerning programs and current research. Contains link to the ocean sciences
teacher resource page, The Bridge.
http://www.vims.edu
Patterson, Mark. 2000. The World of Phyto- and Zooplankton: Life at Low
Reynolds Number. Virginia Institute of Marine Science.
Photographs and graphics used in this lesson are courtesy of NOAA Photo
Library and the Mathematics & Science Center.
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