How to use algae to evoke inquiry and establish interdisciplinary connections

How to use algae to evoke inquiry and
establish interdisciplinary connections
Claudia Bode, Mary Criss, Andrew Ising, Sharon McCue,
Shannon Ralph, Scott Sharp, Val Smith, and Belinda Sturm
E
very year, high school students hunch over microscopes and peer
at a plethora of tiny creatures. Swimming single-celled protists
and whirling multicellular rotifers often steal the show, preventing students from noticing the static algae. However, these frequently
overlooked, ordinary algae are inspiring research all over the world as
scientists contemplate the idea of using algae as a renewable alternative
to fossil fuels. By shifting the focus of their timeless microscope activities, teachers can introduce students to this idea.
This article provides an overview of several algae activities that
teachers can incorporate into their microscope activities to engage high
school students in authentic inquiry—whether in a general or advanced
biology, environmental-science, pre-engineering or biotechnology elective or in a summer enrichment course. Teachers can use individual
lessons or a combination to encourage a wide variety of interdisciplinary connections—building bridges between biology, chemistry, environmental science, engineering, geography, physics, social studies, and
language arts. A complete description of each activity is available online (see “On the web”).
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Why algae?
Most people tend to think of algae as the green, hairlike
fibers that muck up ponds, but the microscopic varieties may
have the most potential as an extraordinary energy source.
Microscopic algae, or microalgae, are rich in oil molecules
called triglycerides. Just like oils from soybeans and peanuts,
a transesterification reaction can chemically convert algal oils
into biodiesel (Chisti 2007).
There are many benefits to microalgae as a fuel source.
For example, algae avidly consume carbon dioxide during
photosynthesis, which helps mitigate greenhouse gas effects.
Algae can also grow in areas unsuitable for standard agriculture, so they don’t compete or interfere with food production.
Whereas soybeans yield about 446 liters of biofuel per hectare annually, microalgae could yield more than 58,000 liters
(Chisti 2007).
A real-world mystery
Despite the potential of algae-derived fuel, many questions
remain. For example, how can scientists and engineers grow
huge quantities of algae and minimize water usage, energy
consumption, and cost? How can they extract algae’s oils
without using harmful organic solvents? From feedstock to
tailpipe, scientists and engineers are working together to turn
algae into a viable fuel in the following ways:
◆◆
◆◆
◆◆
◆◆
◆◆
Ecologists and environmental engineers are searching
for ways to grow algae without compromising land and
water resources.
Chemists and chemical engineers are searching for
benign methods to extract oil from algae and convert it
to fuel.
Mechanical engineers are optimizing how engines
perform with alternative fuels.
Environmental engineers are testing emissions to see
how renewable fuels compare to fossil fuels.
Chemists and chemical engineers are identifying ways to
turn by-products from algae processing and conversion
(e.g., glycerol from biodiesel production) into paints,
plastics, fibers, and other consumer products.
Because practical solutions to these challenges are still uncertain, this area of study is ripe for inquiry—allowing high
school students to work on some of the same key problems
as practicing engineers and biologists. Along the way, students engage in the practices of engineering design, allowing “them to better engage in and aspire to solve the major
societal and environmental challenges they will face in the
decades ahead” (NGSS Lead States 2013, p. 1).
Algal Awareness activity
Teachers can use the microscope to introduce students to
algae and its potential as a biofuel feedstock. In the Algal
Awareness activity (see “On the web”), students examine
pond water samples and learn about a variety of algal species, such as the spikey green rods of Ankistrodesmus and the
spherical clusters of Pediastrum (Figure 1). (See “On the web”
for a link to other freshwater algal images.) This activity
serves as the starting point for further inquiry.
How to grow algae
To set the stage for inquiry, teachers can ask students to think
about how to grow algae. Most students recognize that algae need light, nutrients, water, and air. But how much light
should be provided? What amounts and types of nutrients?
Will a single algal strain grow better than a pond water mixture of multiple algal species? With so many variables to
consider, students can explore various conditions and maybe
even make new discoveries. Four review articles can provide
students useful background knowledge: Demirbas 2008;
Mascarelli 2009 a, b; Pienkos and Darzins 2009.
Students can investigate how to grow algae by using the
Green Machine activity (see “On the web”) and the Maximizing Algal Growth activity (see “On the web”). Alternatively,
described below is an open-ended inquiry approach where
students design and build their own photobioreactors. The
class can work together on a single investigation or divide
into small groups.
Building photobioreactors
Designing and building photobioreactors is more timeconsuming than a guided lab, but it exposes students to an authentic engineering experience. This process gives students the
skills to become independent, creative problem-solvers.
Fun with photobioreactors.
Photobioreactors provide many opportunities for further research and side projects—the only limiting factors
are time and student interest. For example, students can use three tanks to test the impact of climate change,
air pollution, and water pollution on algal growth. This can help them gain a better understanding of population
dynamics and ecosystem health.
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Pond Power
FI G U R E 1
Collecting algae from pond water.
CLOCKWISE FROM FAR LEFT: MARY CRISS; WIKIMEDIA; PETER SIVER, CONNECTICUT COLLEGE.
Clockwise, from left: Sharon McCue, biology teacher, collects algae from a local pond during her summer research
at the University of Kansas; Pediastrum; Ankistrodesmus.
The cost and time investment for growing algae varies.
Though this activity works best as a monthlong project, as
little as one week can be effective since microalgae can grow
rapidly, often doubling in 24 hours. Teachers should allow
one lab period to set up the photobioreactors and 10 minutes twice a week for measuring growth. The supplies (e.g.,
aquaria, pumps) cost from $10 to $50.
The goal of this inquiry is to find a way to maximize algal
growth. After introducing the potential for algae as a biofuel, teachers ask students to take an hour and plan their own
experimental investigation and photobioreactor setup by answering the following questions (for a handout, see Project
Guide Worksheet “On the web”). Teachers must approve the
plan before students proceed to the next step.
1.
Inquiry: What question do you intend to answer with
this project? Some possible questions include:
a. How does the light source or intensity affect algal
growth?
b. What is the ideal nutrient composition, water tem-
perature, pH, or dissolved oxygen level?
c. Will providing aeration, extra carbon dioxide, or
other nutrients accelerate growth?
2. Project design: How will you answer your question?
List each step as specifically as possible and then sketch
the experimental design. (Note: Students’ responses to
this question are typically too general; they struggle to
think through each step and forget to consider details
like variable control, the location of the light source, and
how to hang the light source. Figure 2 (p. 46) lists possible supplies.)
3. Data collection: What data will you collect and how often? How will you present your data? Sketch graphs,
tables, or charts for your data collection. See the following section for how to measure algal growth.
Also, what safety or ethical concerns exist? How will you
deal with each of these? (Safety note: Students must follow
safe lab procedures, including wearing eye protection, wash-
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ing hands, wearing gloves when handling hazards like fertilizers, avoiding skin contact with organisms, disposing of materials appropriately, using caution with electric equipment
near water sources, and using caution when collecting samples from outdoor ponds or streams [don’t use septic ponds].)
Monitoring algal growth
Students need 10–20 minutes per class period to measure
algal population changes and record observations such as
color, smell, and degree of clarity. To monitor algal growth,
students can use turbidity tubes, turbidity meters, spectrophotometer absorbance at 684 nanometers, and hemocytometers. Two high school teachers in our program correlated turbidity data with cell count data from a dozen
different pond water samples (Figure 3) and found that
turbidity tubes are reliable. Students can construct their
own turbidity tubes for about $7 each (see “On the web” for
construction details and a general discussion of turbidity).
Assessment
There are many ways to assess this activity. To build communication skills, we ask students to explain their research in
a formal presentation to family, friends, classmates, teachers,
and even professors and students from area universities (for a
rubric, see “On the web”). In addition, teachers can ask their
students to use social media sites, write blogs, create posters,
and write articles for various outlets (e.g., newspapers, science magazines, peer-reviewed journals). In our experience,
students often struggle to graph data without step-by-step
directions, so we spend extra time critiquing graphs for appropriate axes labels, scales, legends, and titles in their presentations. We also ask students to reflect on the experience
FI G U R E 2
Supplies for photobioreactors.
MARY CRISS
Clockwise, from top, left: Aquaria of microalgae, fluorescent lights to promote algae growth, light timer, air stone
for diffusing air, and gang valve to distribute air from pump to aquaria. Other supplies, not pictured, include algae
source, water source, containers for collecting algal samples, nutrient source, and dissolved fertilizer. Safety note:
Electrical components near water tanks must have ground fault circuit interrupters to prevent electrical shock.
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by answering the following questions:
1. Collaboration: Identify the people who
improved your project’s quality, and
describe their contributions. Collaborators may include classmates, school
staff, family and community members, and professionals.
F IG UR E 3
Correlation between cell count and turbidity.
2. Conclusion/analysis: What answer(s)
did you get to your question? What
trends did you notice? What data
stood out? What additional knowledge did you gain?
3. Reflection: What difficulties did you
encounter with your project, and
how did you deal with challenges?
What new questions do you have as
a result of your project?
Top-Down Trophic Cascade
activity
One of the problems with growing algae for biofuel production in open ponds is that grazing zooplankton—such
as Daphnia, which are transparent crustaceans or “water
fleas”—eat it. Scientists are searching for ways to limit this
feeding frenzy, and biology or environmental studies students can help investigate such food chain effects by manipulating a simulated ecosystem with the Top-Down Trophic
Cascade activity (see “On the web”; Smith 2011).
Begin the activity by establishing four thriving algae
tanks, two of which serve as unmanipulated controls. To
each of the other two tanks, add 10 Daphnia, available from
biological supply companies. Students monitor and graph algal growth for three weeks, then add one or two goldfish,
which eat the Daphnia, to each experimental tank. As the algae thrive, students observe how different organisms interact
with each other and their environment, bringing to life environmental issues and solutions.
seaweed, filamentous “pond scum”), which often bloom in
ponds and streams because of fertilizer runoff and other
forms of pollution. Macroalgae typically have fewer lipids
than microalgae (3–4% of the total algal dry weight compared to 40%) and consist mainly of carbohydrates.
Scientists can manually rake macroalgae, which are easy
to harvest, out of the water and then ferment them to make
ethanol or burn it to heat stoves or furnaces. Though scientists don’t use macroalgae to make biodiesel, they can still
dry them and turn them into a fuel source. We developed
an inexpensive apparatus and lab activity for this process
(Figure 4, p. 48).
Assessment
Teachers can use the following questions to promote classroom discussion or serve as pre- and posttest assessments:
◆◆
Macroalgae: Pond scum or energy source?
In the Drying Algae and Calorimetry activities (see “On
the web”), students can investigate macroalgae (e.g., kelp,
◆◆
Can scientists turn unwanted pond scum into a cheap
source of renewable energy? How?
What are the differences between macro- and
microscopic algae? Which is easier to harvest?
Unexpected drama in the “Top-Down Trophic Cascade” activity.
In one of our classes, students wondered what would happen if we added a crayfish, named Mr. Pinchers, to one
of the Daphnia- and algae-filled tanks. The teacher consented, and the Daphnia clustered around Mr. Pinchers, as
if seeking shelter from the goldfish predator. The teacher eventually rescued Mr. Pinchers from the tank, and the
goldfish ate all the Daphnia over the weekend. The experiment was a success, even if no one witnessed it.
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FI G U R E 4
Drying chamber for dewatering macroalgae.
MARY CRISS
Make the chamber using a Styrofoam cooler, small box, hair dryer, and window screen. Spread algae evenly on the
drying screen. Record the mass at time zero. Blow-dry for one minute and record the mass. Repeat until mass levels
out (about 10 minutes). Pelletize the dried algae using a 5-milliliter syringe. After compressing the syringe as hard as
possible, use a paper clip to push the pellet away from the end of the syringe. Remove the plunger and allow the
pellet to dry overnight. If desired, use a calorimeter activity (see “On the web”) to calculate the energy content of
the algae pellet. (Safety note: Styrofoam product should be flame retardant [check label]. Only run dryer on lowest
setting. Monitor at all times and do not overheat. Have an ABC fire extinguisher handy and know how to use it.)
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Pond Power
In these activities, students discover that pond scum is
mostly water, with only about 10% biomass. This observation
leads to a thought-provoking dilemma that makes a good
written report or classroom discussion: Though macroalgae
are cheap and abundant, are they worth all the trouble (and
energy) to harvest and dry? If harvesters manually collect
macroalgae from polluted areas, how might this affect the
harvesters’ health or that of the ecosystem?
We ask students to perform a qualitative benefits verses
barriers analysis to see how engineering and biological concepts incorporate socioeconomic and global issues. Though
macroalgae present many clear limitations as a fuel source,
students can brainstorm creative, innovative solutions to
these barriers.
Interdisciplinary connections
In much the same way that Weyman (2009) described the interdisciplinary connections of biofuels, teachers can use the
activities described here to connect neighboring intellectual
terrain, foster problem-solving skills, and help students develop appreciation for ethical and environmental concerns.
Students use skills from the following subjects:
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◆◆
physics: to test the effects of light intensity and
transmission,
chemistry: to calculate molar concentrations for
nutrient-rich media,
◆◆
math: to graph data and perform statistical analyses,
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English: to write reports, and
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social studies and geography: to appreciate regional
socioeconomic concerns and climate and land-use
issues.
Conclusion
From microscope to photobioreactor, algae is an effective
tool to relate common biology concepts to real-world challenges like renewable energy. The area is not only ripe for
inquiry, but students can make observations, pose questions,
and gather and analyze data. n
Claudia Bode ([email protected]) is an education director at the
University of Kansas in Lawrence; Mary Criss (mcriss@usd259.
net) is a biology teacher at Wichita North High School in
Wichita, Kansas; Andrew Ising ([email protected]) is a biology teacher at Olathe North High School in Olathe, Kansas;
Sharon McCue ([email protected]) is a biology teacher at
Wichita Northeast Magnet High School in Wichita, Kansas;
Shannon Ralph ([email protected]) is a biology teacher at Dodge City High School in Dodge City, Kansas; Scott
Sharp ([email protected]) is a biology teacher at De Soto High
School in De Soto, Kansas; Val Smith ([email protected]) is a professor at the University of Kansas in Lawrence; and Belinda
Sturm ([email protected]) is an associate professor at the University of Kansas in Lawrence.
About the project
The activities described here were developed at a National Science
Foundation Research Experiences for Teachers program called
Shaping Inquiry from Feedstock to Tailpipe (NSF EEC-0909199).
With funding from the American Recovery and Reinvestment
Act, this program engages high school and community college
instructors in biofuel-related projects at the University of Kansas.
On the web
Algae research rubric: http://bit.ly/1bfmWNx
Algal Awareness activity: http://bit.ly/1bdK6Hq
Algal blooms at the 2008 Olympics video: http://bit.ly/1k6WOd7
Calorimeter activity: http://bit.ly/1jhpbrB
Daphnia: Birth of the Next Generation video: http://bit.ly/1eM2Wq5
Daphnia videos from Video Image and Data Access: http://bit.
ly/1jhppyW
Directions for making a turbidity tube: http://bit.ly/1av5EMj
Drying algae activity: http://bit.ly/1eM3g8d
Freshwater algae images: http://fmp.conncoll.edu/Silicasecchidisk/
LucidKeys/Carolina_Key/html/Group_List.html
Guppies Eating Daphnia video: http://bit.ly/1k6XKhE
Maximizing Algal Density activity: http://bit.ly/18f2FuI
Project guide worksheet: http://bit.ly/1iwe2VX
The Green Machine: Making Algae Grow activity: http://bit.ly/
IqtMcV
Top-down trophic cascade activity: http://bit.ly/1cjC2Gx
References
Chisti, Y. 2007. Biodiesel from microalgae. Biotechnology
Advances 25 (3): 294–306.
Demirbas, A. 2008. Production of biodiesel from algae oils.
Energy Sources, Part A 31 (2): 163–168.
Mascarelli, A.L. 2009a. Algae: Fuel of the future? Environmental
Science and Technology 43 (19): 7160–7161.
Mascarelli, A.L. 2009b. Gold rush for algae. Nature 461
(7263):460–461.
NGSS Lead States. 2013. Next Generation Science Standards: For
states, by states. Washington, DC: National Academies Press.
Pienkos, P.T., and A. Darzins. 2009. The promise and challenges
of microalgal-derived biofuels. Biofuels, Bioproducts &
Biorefining 3 (4): 431–440.
Smith, V.H. 2011. The ecology of algal biofuel production.
ActionBioscience.org, www.actionbioscience.org/biotech/smith.
html
Sturm, B.S., E. Peltier, V. Smith, and F. De Noyelles. 2012.
Controls of microalgal biomass and lipid production in
municipal wastewater-fed bioreactors. Environmental Progress
& Sustainable Energy 31 (1): 10–16.
Weyman, P.D. 2009. The interdisciplinary study of biofuels. The
Science Teacher 76 (2): 29–34.
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