Introduction to Agriculture, Food, and Natural
Resources
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Introduction to Agriculture, Food, and Natural
Resources
Dichotomous Keys
Unit 4 – Lesson 4.2 The Order of
Classification
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What is a Dichotomous Key?
• A method for determining the identity of
something by going through a series of
choices that leads the user to the correct
name of the item.
• Dichotomous means "divided in two parts“
• Somewhat like playing the game “20
Questions”
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Using Dichotomous Keys
Start by observing the item to be identified.
List the most general traits of that item.
At the beginning of the key, select the
choice that best describes your item.
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Using Dichotomous Keys
Each step will involve making a choice
between two characteristics.
Each statement should lead you to the
next step to narrow the selection further.
Each step will either identify the item or
direct you where to go next in the key.
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Example
1. If the object is used for writing, go to 2
1. If the object is used for organizing go to 3
2. The object makes a gray mark…pencil
2. The object makes a blue mark…pen
3. The object is metal...paper clip
3. The object is elastic…rubber band
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References
Detka, J. (2009). Designing and using a
dichotomous key. Retrieved from
http://watershed.csumb.edu/ron/roncor/cor/did.ht
m
Enchanted Learning. (2010). Make a dichotomous
key. Retrieved from
http://www.enchantedlearning.com/subjects/plan
ts/activity/key.shtml
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