1. Dichotomous Keys

2. A dichotomous key - method for determining the identity of something by going through a series of choices which leads to the correct name of the item.

3. Dichotomous means
"divided in two parts".

4. At each step of the
process of using the
key, the user is given
two choices.

5. It's like playing 20 questions
Each alternative leads to another question until the item is identified.
It's like playing 20 questions
or Guess Who.

6. For example, a question in a dichotomous key for
trees might be something like:
"Are the leaves flat or needle-like?"

7. If the answer was "needlelike”,
then the next question might be something like:
"Are the needles in a
bunch or are they spread
along the branch?” Eventually, when enough questions have been
answered,
the identity of the tree is revealed. .

8. Classroom Activity: As a simple example, you can construct a
dichotomous key to identify people (or another
group of items) in a classroom, using questions
based on gender, hair length/color, glasses
(or not), clothing color, etc.
Question 1: Is the person male or female? Question 2: Does the person wear glasses or not? Question 3: Is the person wearing blue jeans or not? etc.
The end of each branch of the key should be a person's
name.
A dichotomous key will have enough questions to identify
each member of the group. To test it, you can identify each person in the group by going through the key and seeing if
the right name comes up.

9. 10 Common Mammals of Georgia
Example: Page 226 in the Holt Book
Dichotomous Key to
10 Common Mammals of Georgia

10. Lets
classify a
Cereal !

11. Use a dichotomous key to identify this cereal.

12. Is it rice?
If yes
If no
Rice Krispies
Go to 2
2. Is it flakes?
Go to 3
Cheerios
3. Does it have fruit?
Go to 5
Go to 4
4. Does it have sugar?
Frosted Flakes
Corn Flakes
5. Does it have berries?
Special K with Berries
Go to 6
6. Does it have raisins?
Raisin Bran
Granola Flakes with Bananas

13. rice
yes
Rice Krispies
Frosted Flakes no
yes no
yes
flakes
fruit
sugar no
yes no
Kellogg's Corn Flakes
Cheerios
yes
berries
Special K with Berries no
yes
raisins
Raisin Bran no
Granola Flakes with Bananas

14. Raisin
Bran

15. Make your own dichotomous key. Get a topic from your teacher
You must have a minimum of
6 steps.