Classification What are Dichotomous Keys? a method for determining the identity of something (like...
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Transcript of Classification What are Dichotomous Keys? a method for determining the identity of something (like...
![Page 1: Classification What are Dichotomous Keys? a method for determining the identity of something (like the name of a butterfly, a plant, a lichen, or a rock)](https://reader036.fdocuments.in/reader036/viewer/2022062515/56649ced5503460f949ba86c/html5/thumbnails/1.jpg)
Classification
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What are Dichotomous Keys?
• a method for determining the identity of something (like the name of a butterfly, a plant, a lichen, or a rock) by going through a series of choices that leads the user to the correct name of the item.
• A dichotomous key is a listing of characteristics, such as structure and behavior, organized in such a way that an organism can be identified or classified.
• Think of a dichotomous key as a type of scavenger hunt.
• Dichotomous means "divided in two parts".
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Using a dichotomous keyAt each step of the process of using the key, the user is
given two choices; each alternative leads to another question until the item is identified.
1a. If the leaves are flat….go to question 4. 1b. If the leaves are needle-like….go to question 2.2a. Are the needles in a bunch? Go to question 52b. Are they spread along the branch?“…pine tree
Eventually, when enough questions have been answered, the identity of the tree is revealed.
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DICHOTOMOUS KEY EXAMPLE
1. a. tail fins are horizontal—whale………………….go to 2 b. tail fins are vertical—fish……………………….go to 32. a. has teeth or tusk—toothed whale………………..go to 4 b. has no teeth………………………...BALEEN WHALE3. a. has gill slits behind mouth—shark…….………...go to 5 b. has no gill slits……………………..NONSHARK FISH4. a. black with white underside………….KILLER WHALE b. tusk, gray with dark spots………………....NARWHAL5. a. head is hammer-shaped……..HAMMERHEAD SHARK b. tail is half the body length……….THRESHER SHARK
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MAKING A DICHOTOMOUS CLASSIFICATION KEY
http://www.qacps.k12.md.us/ces/Staff2.htm
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POSSIBLE“DERIVED CHARACTERS”
• All made of one material
• Is it hinged
• Has a sharp edge
• Has holes
• Hammer-like head
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Hammer-like head Other types of head
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Hammer-like head Other types of head
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Hammer-like head Other types of head
ALL Made of Wood
Made of Wood and other materials
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Hammer-like head Other types of head
Sides of head are different
Sides of headare same
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Hammer-like head Other types of head
Sides of head are different
Sides of headare same
All wooden NOT all wooden
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Hammer-like head Other types of head
Sides of head are different
Sides of headare same
All wooden Wooden and rubber? ?
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Engage Activity –Create your own dichotomous key
Create a dichotomous key to identify 2 people in this classroom, using questions based on gender, hair length/color, glasses (or not), clothing color, etc.
1a. Is this person male? Go to question 2.
1b. Is this person female? Go to question 3.