Frank C. Martin K-8 Center Department of Science
Student Name:__________________________________ Period:________ Date:_________
Classification Lab
Classification is the process of organizing different objects into categories based on their
common characteristics. Think about the dresser in your bedroom. Typically, one drawer is
used for shirts, another for shorts, and yet another for socks. Each clothing item was classified
based on how it is worn, and is then grouped with similar clothing in the dresser drawer.
Taxonomy
A similar process is used in life science to group organisms. There are numerous different
organisms in the universe, each with a unique set of characteristics. To organize them,
scientists use a system called taxonomy. Taxonomy is the science of identifying, naming,
organizing, and classifying organisms. Imagine that you are looking out your bedroom window
at a beautiful tree. You may be seeing a tree with leaves, or one with needles, fruit, or nuts.
There are many different types of trees, but all trees share some characteristics such as having
roots and branches. Using the process of taxonomy, scientists can discover characteristics that
certain organisms, such as trees, have in common and group them into appropriate categories.
What is a
Concepts covered
• Taxonomy
• Linnaean System
• Dichotomous Key
Linnaean System
Though there is more than one system used to classify objects, science most commonly uses
the Linnaean system to group organisms. Originally developed by Carolus Linneas in the
mid‐1700s, this system is used to classify organisms starting with the broad grouping and
ending with the most specific. Though the system has changed somewhat since Linneas’ time,
the general hierarchy he created remains intact. Linneas came up with a tiered structure for
classifying objects. Currently, the tiered system starts with domain and works down through
kingdom, phylum, class, order, family, genus, and species.
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As you move down the classification line, the categories become more specific. A concept
known as binomial nomenclature (two‐part name) was also created by Linneas. Binomial
nomenclature is a scientific name given to every organism that consists of its genus and its
unique species name. For example, humans are in the genus Homo and have a species name of
Sapien. So the binomial nomenclature name for humans is Homo Sapien. .
A useful tool to help remember the order of the Linnean classification system can be developed
by using a mnemonic phrase. Each of the first letters of the mnemonic phrase are the same first
letter of the corresponding classification category (i.e. Daring = Domain, Kids = Kingdom, etc.).
For example, Daring Kids Pick Cauliflower Over Fresh Grown Strawberries. Try to make your
own to help you remember!
Dichotomous Key
A dichotomous key is a scientific tool used to determine the identity of an organism. This
process is accomplished by going through a series of choices that eventually lead to the correct
name for that organism. At each step of the key, two choices are given. The organism will fit
into only one of the choices, allowing one to proceed to the next question until the organism is
clearly identified. For example, if there was a flower petal on the table, one question in the
dichotomous key may be: “Does the flower have red coloring or purple coloring?”. Answer that
question and move onto the next corresponding question which may be something like: “Is the
petal over or under five inches from base to tip?”. As the questions are answered, the organism
becomes more precisely classified until the specific identity of the organism is determined.
Always be sure when creating a dichotomous key that the characteristics being used remain
constant. It would be difficult to classify an object if the dichotomous key asked about
characteristics the organism only displayed at certain points in time. Also, be sure to use actual
measurements rather than subjective words such as big, small, large, tiny, etc.
Lab: Button, Button, Whose Got The Button
Button Lab - Taxonomy is the study of classification. You will use buttons to practice
classification. You will also make up a dichotomous key associated with your population of
buttons.
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Get a jar with 20 buttons in it
Set your paper on its side (landscape)
Write the word "Buttons" at the top center of the page.
In parenthesis under the word write the number you have. It should be 20.
Divide the buttons based on "have" and "have not." The first separation should divide
the buttons into 5 & 5 or 4 & 6. For example: # of holes/not that # of holes, color/not
that color, size/not that size, texture/ not that texture, material/ not that material,
ridge/ no ridge, design/not that design...
6. Try to use different descriptions for each of the divisions.
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7. Keep dividing until each button is alone. In other words, under the description is a one
(1) in parentheses.
8. Number each division 1 - 9; you'll use it later for the dichotomous key.
9. Name the buttons using the previous division for the first name and the final division for
the second name. Add a "-us" to make is sound Latin and if it's a part of the "not"
division, use “A”-, or –“Un”, or –“Non” before the description. (For example: if the
previous division stemmed from "big" and the final division was "blue" and "not blue",
then one button would be Bigus blueous and the other would be Bigus nonblueous.
10. Now make a dichotomous key using the handout provided. This key reorganizes the
divisions you just made into a list.
11. Test your key, by having a neighbor classify at least three different buttons.
How to Develop a Dichotomous Key
Introduction: The word dichotomous comes from the combination of several Greek phrases
and means “division into 2 equal parts”. Dichotomous keys are based on taxonomic
characteristics of organisms. Scientists use dichotomous keys to sort most everything. Keys are
arranged in an either/or pattern according to specific characteristics. The key leads you through
a series of either/or characteristics. This process eventually helps you to eliminate everything
but what you have. Although some keys seem very difficult, it’s usually the vocabulary that
stumps you.
The basics for developing a dichotomous key:
1. Identify the characteristics of similar items.
2. Divide the items into 2 groups according to a common characteristic.
3. Once you have the items in two separate groups, decide another characteristic to further
divide the grouped items into even smaller groups.
4. Continue until you have identified each item by a unique characteristic.
Keys can be organized as text or as a line drawing. A text example is below. We will use
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