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2/23/15 Starter: 169 170 Application/Connection: Sports Dichotomous Key Exit: 2/23/15 Practice: Paste Notes here Dichotomous Keys notes Summarize what you learned in the lab. Why do you think a classification system is important? Dichotomous Keys notes
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1 Starter 2. Notes 3. Activity February 23 2015 AGENDA B.8A Define taxonomy and recognize the importance of a standardized taxonomic system to the scientific community ELPS. c1C, c1E
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Date Lecture/ Activity/ Lab Page 2/12 Ordering Fossils Activity 161-162 2/13 Evidence of Fossils 163-164 2/17 Test Review 165-166 2/19-20 Classification 167-168 Table of Contents
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A dichotomous key is a tool that scientists can use to identify an unknown organism or specimen.
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Examples include… insects
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trees
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rocks
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and shells.
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The word dichotomous means “divided in means “divided in two parts.”
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Characteristics of a Dichotomous Key Dichotomous Key
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Consists of a series of two part Consists of a series of two part statements that describe the characteristics of a specimen.
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The user is presented The user is presented with two choices.
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As the user makes a choice, they are led to a new branch of the key.
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In the end, the user is led to the name of the specimen. In the end, the user is led to the name of the specimen.
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Constructing a Dichotomous Key
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Separate the Separate thespecimens into two groups based on one characteristic.
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Example: A deck of playing cards could be separated into black cards and red cards.
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Continue to separate the groups until each specimen has its own set of characteristics. Continue to separate the groups until each specimen has its own set of characteristics.
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Example: Red cards can be separated into hearts / diamonds, then picture / number cards then male / female cards, etc.
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Make the choice a positive one – for example, something “is” instead of “is not.”
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Example: 2a.Black card is a spade…….4 2b.Black card is a club……….5 4a.Spade is a picture card…6 4b.Spade is a number card…7 6a.Picture card is male……….8 6b.Picture card is female…..9
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Start both choices in a pair with the same word.Start both choices in a pair with the same word.
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Example: 2a.Red card is a heart……….4 2b.Red card is a diamond……5
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Start the next pairStart the next pair with different words.
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Example: 2a.Red card is a heart……….4 2b.Red card is a diamond……5 4a.Heart is picture card…….6 4b.Heart is number card…….7 6a.Picture card is male……….8 6b.Picture card is female……9
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There should be one less step than the total number of specimens to be identified.
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5/13/13 Starter: 141 142 Connection/exit: 5/13/13 Practice/Application: Paste Review sheet here when done Dichotomous Keys notes List the five features that describe living things.
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