1. Classification of Organisms & Dichotomous Keys
7th Grade Science

2. Classification of Organisms
Scientists classify organisms to learn more about them
Organism--any living thing

4. Aristotle
The Greek philosopher Aristotle was the first person to scientifically classify living things. He classified things as plants or animals. Later he subdivided organisms even farther.

5. Carolus Linnaeus
In the 1700’s Carolus Linnaeus created a different classification system based on similarities in structures.
Called “the father of taxonomy”
Latinized his own name from Carl Linne’
Came up with a way to classify organisms with a two name naming system (binomial nomenclature) that would be universal to scientist all over the world.

7. Classification Hierarchy
Domain
First level is domain
There are 3 domains: Archaea, bacteria, and eukarya

8. Classification Hierarchy
The kingdom level is broken down into six smaller levels.
These include phylum, class, order, family, genus, and species.
Each level contains fewer types of organisms than the level before.
The species level includes only one type of organism.
Organisms become more closely related as you move from kingdom to species level.

9. Classification Hierarchy
Organisms are called by their scientific name, which consists of the genus and species names. Example: Homo sapiens - humans
Homo is the genus name
Sapiens is the species name.
Written in italics or underline
Genus capitalized and species lower case

10. Classification Hierarchy
Remember the order with the saying Dear, King, Phillip, Came, Over, For, Great, Spaghetti.
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Many common names may be given to the same organism.
An organism has only one scientific name and that name is the same for scientists all over the world.

13. 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.

14. Dichotomous Keys
Think of a dichotomous key as a type of scavenger hunt.
Dichotomous means "divided in two parts".
At 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

15. Dichotomous Key in Diagram Form

17. Dichotomous Key Example
1a Flat sides > Go to 2
1b Not flat sides > Go to 3
2a 4 sides > Kingdom Rectangles
2b 3 sides > Kingdom Triangles
3a Constant radius (3D) > Kingdom Spheres
3b Not constant radius (3D) ----> Go to 4
4a Constant radius (2D) > Kingdom Cylinder
4b No constant radius (2D) -----> Kingdom Heart (etc.)

18. Example