Classification Activity

Teachers notes

Missouri Grade-level Expectations:  3.1.E.a, 3.1.E.b

Concept:  Classification and taxonomy explore the evolutionary relationships between different organisms.  Students will explore the process of classifying items based on physical traits.

Activities:  This learning cycle activity begins with students receiving a bag that contains various household items (screws, nuts, bolts, sponges, paperclips, etc.).  In groups of two, students will organize the various items into 4 different categories (student derived) based on their physical features and record the criteria for each category.  Groups then trade their criteria sheet with another group and try to classify the items in the new categories.  A class discussion will follow analyzing the purpose for classification and how different perceptions can influence where items/organisms are placed.  Finally, students will apply the concept to develop a dichotomous key used in identifying several organisms.

Data collected:  Students record their criteria for the 4 categories they will separate the household items into.  On a separate data sheet they will also record which items belong in each category.

Concept introduction:  Students will read about early classification systems and explore current ideas and factors influencing organism taxonomy.  A discussion on DNA sequencing will highlight how genetic analysis has modified the criteria for placing organisms in certain taxa and has enhanced our understanding of evolution.

Application:  Students will design a dichotomous key for identifying various organisms based on physical characteristics.  Students could then trade their dichotomous keys with each other to see if they can properly identify each organism using the key.

Materials:

-12 paper bags containing 20 small household items (Each bag must contain the same items).

-Items could include:  screws/nails of various lengths and sizes, electrical adapters, sponge, bolts, nuts, toothpicks, paper clips of different sizes, Q-tips, nail files, coins, etc.  **You'll need at least 12 of each item, 1 per bag.

-Several leafy conifer stems for identification.  Can use pine, fir, spruce, etc.  You will need a minimum of 12 stems for a class of 24.

-Minimum of 10 insect or arthropod specimens.  Students could collect these several weeks in advance in a different lesson.

History:  Aristotle (384-322 B.C.) is credited as the first person to classify living organisms, although he only had two main categories:  plants and animals.  In the 1700's Swedish naturalist Carolus Linnaeus developed a two-word naming system for all organisms.  This binomial nomenclature used Latin as the language of choice and grouped similar organisms into the taxa currently used today:  kingdom, phylum, class, order, family, genus, species.  However, it wasn't until 1866 when German Ernst Haeckel proposed a third kingdom, Protista, to contain single-celled organisms.  A fourth kingdom was added in 1938 by American Herbert Copeland to classify all bacteria (prokaryotes) in the kingdom Monera based on their lack of nuclei.  In 1957 a fifth kingdom was proposed by American Robert H. Whittaker to include Fungi based on their unique way to gather food.  Finally, in 1990 American microbiologist Carl Woese proposed a new category above kingdom called domain which grouped all organisms based on their type of RNA.  The three domains include Archae, Bacteria, and Eucarya.

Related websites:

http://www.sidwell.edu/us/science/vlb5/Labs/Classification_Lab/classification_lab.html

http://qldscienceteachers.tripod.com/junior/biology/class.html

http://anthro.palomar.edu/animal/animal_1.htm

http://goode.si.edu/webnew/pages/nmnh/TaxonomyQuery.php

http://library.sandiegozoo.org/Fact%20Sheets/bear_polar/polar.htm#2

http://www.dsisd.k12.mi.us/mff/TreeBasics/TreeIDspplist.htm#Fagaceae

http://ology.amnh.org/biodiversity/treeoflife/pages/cladogram.html

http://oregonstate.edu/trees/dk/start.html

Sources:

Classification of organisms (2005), MSN Encarta, December 1, 2005, Online source.

Mader, S.S. (2001), Biology, 7th ed. McGraw Hill:  Boston

Michigan Forests Forever Teachers Guide (2005), Michigan State University Extension, December 3, 2005, Online source

Polar bears (2001), San Diego Zoo, December 3, 2005, Online source

http://en.wikibooks.org/wiki/Dichotomous_Key