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Teaching
With C-Fern
Integration
with National Science Education Standards
The National
Science Education Standards (1996. National Research Council. Washington
D.C. )comprise
an integrated set of standards for science teaching, professional development
for teachers of science, assessment in science education, science content,
science education programs, and science education systems with the ultimate
goal of developing a scientifically literate populace. While the value
of C-Fern as a model system make it useful for many of the standard
sets, here we focus on the application C-Fern in the Science as
Inquiry and the Life Science Content Standards.
Science
as Inquiry
As a central
focus of the National Standards, inquiry-based learning requires that
students be given the opportunity to develop skills in asking questions,
designing and conducting investigations, using tools to collect data,
critically evaluating experimental results and communicating the results
and implications of scientific studies. Several features make C-Fern
ideal for inquiry-based and individual or group experimental approaches.
During the rapid two-week development of C-Fern, from spores to
sexually mature gametophytes, many biological processes are easily observed,
manipulated and measured. For instance, spore germination (absolute or
over time) can be quantified and used to assess the organism's responses
to environmental stresses. Also, changes in gametophyte sex ratio (pheromone-based)
can be quantified to assess the effects of manipulations, treatments or
genotypes within a population. Observations of these and other simple
but varied features provide opportunities to ask and refine many types
of questions. In addition, because C-Fern gametophytes are small,
i.e., 0.5 - 3 mm at maturity, large populations consisting of hundreds
of individuals can be cultured in small (60x20 mm) Petri dishes. Rapid
development of gametophytes means that experiments can be repeated easily
and successive experiments can be easily extended over time. These properties
make it possible to generate very large data sets for individual and classroom-level
experimentation and thus provide an excellent foundation in sampling techniques,
quantitative measurements, statistical treatment of data and interpretation
and communication of results.
Life
Science Content Standards
The broad applicability
of C-Fern for a variety of classroom uses means that it can be
applied and integrated into several of the Content Standards.
Life Science standards focus on the science facts, concepts, principles,
theories, and models that are important for all students to know, understand,
and use.
In the following Table,
the bulleted list highlights some of the specific C-Fern attributes
that are relevant to each standard category.
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Life
Science Standards
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Levels
K - 4
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Levels
5 - 8
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Levels
9 - 12
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Characteristics
of organisms
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Structure
and function in living systems
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The cell
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- plant form
and function
- basic requirements
for plant growth
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- C-Fern
exists as two independent organisms
- gametophytes
allow easy visualization of cell structure and differentiation
- comparative
studies of gametophyte and sporophyte structure and function
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- structure
and function in gametophyte tissues -vegetative, meristematic,
absorptive/anchoring, specialized sperm cells
- cell motility
(sperm)
- chemotaxis
(sperm)
- spores as
single-celled propagules
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Life cycles of organisms
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Reproduction
and heredity
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Molecular
basis of heredity
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- sexual and
asexual reproduction
- non-flowering
plant reproduction
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- C-Fern
clearly shows the relationship of all aspects of sexual reproduction
- genetic studies
with C-Fern allow examination of both haploid (gametophytic)
and diploid (sporophytic) ratios
- a wide variety
of mutant stocks allows extended investigation of the effects
of mutation
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- although
structure and function are very different, C-Fern gametophytes
and sporophytes contain the same genetic instructions
- gametophytes
have ½ the chromosomes of the sporophyte
- sexual differentiation
in gametophytes is related to a chemical control of gene expression
- mutants exist
that have altered responses to the chemical (pheromone) that controls
sexual type
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Organisms
and environment
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Regulation
and behavior
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Biological
evolution
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- responses
to changes in environment (C-Fern can be grown both terrestrially
and aquatically)
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- changes in
sex ratio in response to population size and/or environment
- changes in
sporophyte growth in response to aquatic vs. terrestrial environment
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- ferns have
adapted for a specific lifestyle
- C-Fern
has specialized adaptations for a ‘semi-aquatic’ lifestyle
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Populations and ecosystems
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Matter, energy, and organization of living systems
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- the effect
of population size on sex ratio or early sporophyte development
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- C-Fern
is autotrophic and exhibits distinct adaptations for photosynthesis
and related activities
- C-Fern
gametophyte and sporophyte generations are independently autotrophic
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Diversity
and adaptation of organisms
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Behavior of organisms
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- the structure
and function of the C-Fern life cycle relative to other
plants
- adaptation
to different environments
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- chemotaxis
by C-Fern sperm shows behavior at the single cell level
- C-Fern
shows typical plant responses to the environment
- population
pressures influence development in both gametophytes and sporophytes
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