WhatBelongsin Your 15-Bean Soup? - NSTA Learning Center

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T E A C H I N G S T R A T E G I E S
FIGURE 4
FIGURE 5
Rubric for evaluating taxonomic keys
Able to identify items using the key
Key moves from general to specific
Couplets are indented or there is space between couplets
Quantitative, consistent measurements, not small, large
Precede with noun, followed by verb
Begin choices with same character
Begin couplet with different words
Couplets appropriate in length
Appropriate number of couplets
Use of appropriate vocabulary
Example of a key constructed
by students using communities
of paper fasteners
Comments on the key resulted from peer evaluation by
other student groups.
to enclose related groups—for example,
one loop of yarn could be used to enclose
each “species group,” with a second, larger
Yes No loop enclosing all species included in a
single genus. Once students have sorted
and ranked their groups, they should develop
a classification scheme that reflects
the relative degree of relationship among
the objects.
Once student groups have sorted
their paper fasteners, ranked them, and
developed a classification system, then
they can write a dichotomous key that
would allow other people to identify species
in their paper fastener community.
Evaluation of the keys may be done by
the teacher using a rubric such as that
shown in Figure 4. Alternatively, students
can exchange dichotomous keys and utilize peer evaluation
in a review and revision cycle prior to evaluation by
the instructor. Figure 5 shows peer review comments from
such a review and revision cycle, and indicates an extension
of this classroom activity into standard taxonomic names
assigned to the various paper fasteners.
Conclusion
The application of the Learning Cycle process to taxonomic
principles, hierarchical classification, and construction of
keys presents the components of classification that include
sorting (grouping) and ranking as separate stages in classification.
In addition, it separates production and use of keys
from the classification process and presents it as a useful product
of classification. Students frequently use keys to identify
trees, insects, wildflowers, minerals, or rocks. Understanding
concepts behind the classification process and production
of taxonomic keys will enable the students to select
appropriate keys for their region. A suggested extension is
for the student to find a key from a source such as the
Internet, libraries, bookstores, or state agencies to share with
other students in the class. ■
able from any office supply source. Students are instructed to
sort their paper fasteners into groups equivalent to species,
then rank groups into higher taxonomic categories (genus,
family, etc.). To aid in ranking, they may use yarn loops again
References
Barrett, K., et al. 1992. GEMS: Investigating artifacts. Berkeley, CA:
Lawrence Hall of Science, University of California at Berkeley.
Beisenherz, P. and M. Dantonio. 1996. Using the learning cycle to
teach physical science. Portsmouth, N.H.: Heinemann.
Berlin, B., D. E. Breedlove, and P. H. Raven. 1973. General principles
of classification and nomenclature in folk biology. American
Anthropologist 75: 214–42.
National Research Council (NRC). 1996. National Science Education
Standards. Washington, D.C.: National Academy Press.
Stuessy, T. F. 1990. Plant taxonomy. New York, N.Y.: Columbia
University Press.
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