Post on 01-Jan-2016
description
Dichotomous Key
Using Observable Characteristics
to Identify Objects
What is a dichotomous key?A dichotomous key is a tool that allows the user to
determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish.
Keys consist of a series of choices that lead the user to the correct name of a given item.
"Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.
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.
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
StartUse a dichotomous key to identify these individuals.
Pick an individual to identify, When you are ready click start.
Is the individual male or female?
Male Female
Is the individual wearing a hat?
Hat No Hat
Is the individual in the military?
Military Not Military
Is he wearing a dress uniform or a camouflage uniform?
Dress Uniform
CamouflageUniform
Introducing
He is a man wearing a hat and a military dress uniform.
Arnold
Return to Start
Introducing
He is a man wearing a hat and a camouflage military uniform.
Hector
Return to Start
Introducing
He is a man wearing a hat, but not wearing a military uniform.
Greg
Return to Start
Does the individual have facial hair or is he clean shaven?
FacialHair
CleanShaven
Is the individual wearing black?
WearingBlack
Not WearingBlack
What is the individual wearing?
Suit Jeans
Introducing
He is a man with facial hair, wearing a black suit, but not wearing a hat.
Reggie
Return to Start
Introducing
He is a man with facial hair, wearing a black shirt and jeans, but not wearing a hat.
Hugo
Return to Start
Introducing
He is a man with facial hair who is not wearing black or a hat.
Bill
Return to Start
What is the individual wearing?
Shorts Pants
Introducing
He is a clean shaven man who is wearing shorts, but not black or a hat.
Jack
Return to Start
Introducing
He is a clean shaven man who is wearing pants, but not black or a hat.
Kurt
Return to Start
Is the individual wearing a hat?
Hat No Hat
Is the individual wearing purple?
WearingPurple
Not WearingPurple
What is the individual wearing
Green Boaand Hat
Red Boaand Hat
Introducing
She is wearing a purple dress and green boa and hat.
Doris
Return to Start
Does the individual have a purse?
Purse No Purse
Introducing
She is wearing a purple dress and red purse, boa, and hat.
Erin
Return to Start
Introducing
She is wearing a purple dress and red boa and hat.
Rhonda
Return to Start
Introducing
She is wearing a hat, but not wearing purple.
Gail
Return to Start
What is the individual wearing?
Pants Skirt
Introducing
She is wearing pants, but not a hat.
Jenny
Return to Start
What color boots is the individual wearing?
Red Black
Introducing
She is wearing a skirt and red boots, but not a hat.
Mary
Return to Start
Introducing
She is wearing a skirt and black boots, but not a hat.
Beth
Return to Start
MAKING A DICHOTOMOUS CLASSIFICATION KEY
POSSIBLE“DERIVED CHARACTERS”
• All made of one material
• Is it hinged
• Has a sharp edge
• Has holes
• Hammer-like head
Hammer-like head Other types of head
Hammer-like head Other types of head
Hammer-like head Other types of head
ALL Made of Wood
Made of Wood and other materials
Hammer-like head Other types of head
Sides of head are different
Sides of headare same
Hammer-like head Other types of head
Sides of head are different
Sides of headare same
All wooden NOT all wooden
Hammer-like head Other types of head
Sides of head are different
Sides of headare same
All wooden Wooden and rubber? ?
Objects made of One Material Objects made of more than One Material
Divide the rest of the items until each one has been identified.